Abstract:In order to monitor the seeding performance of no-tillage corn precision seeder in real time, a seeder monitoring system was developed based on photoelectricity induction of infrared reflection. For optical signal acquisition, a detector of monitoring system was designed with infrared emission diode and infrared photodiode as signal transmitting terminal and receiving end. Through evaluating and calculating the monitoring blind area, the structural and installation parameters of detector were optimized. To improve the dust-laden environmental adaptability of monitoring system, a self-cleaning device for dedusting using a rotary transparent dust cover was designed to protect the monitoring system from dust erosion. A hardware circuit of monitoring system with functions of seeding signal acquisition, working speed gathering, dedusting motor control and alarm display was developed. And a software algorithm with time difference of neighbor falling seeds as key parameter was studied to judge normal seeding, seed missing and reseeding. To test the precision of monitoring system, a bench experiment was conducted. The experimental results showed that the monitoring system had accuracies of 98.5% in seeding quantity, 95.1% in seed missing, 85.6% in reseeding, and had an accuracy of 98.1% in seeding quantity in the emulated environment of dust adhesion, which indicated that the monitoring system had high precision in monitoring the seeding performance, and achieved good effect for dedusting. This system can meet the requirement of working monitoring for no-tillage precision seeder, and it can help to improve sowing quality.

Abstract:With the development of specialization and large-scale vegetable planting in China, factory seeding was widely used, and there was high requirement for sowing. Vegetable tray seeding machinery is one of the core equipment of vegetable seedling. In order to solve the problems of low productivity, high labor intensity in manual seeding and the current planting machine being not suitable for the need of small and medium sized planting greenhouses in China, the automatic seeding device used in greenhouses was designed on the base of the analysis of characteristic parameters of rape and cucumber seeds. One side of the seeding device can be folded in order to carry it easily. The size of folded seeding machine was 500mm×500mm×750mm.The device was designed with a multifunctional integrated structure, including hole-punching and seeding, which simplified the working procedure. Both the hole-punching and seeding can be achieved accurately through detecting the position of the notch in the tray by laser sensor. The success rate of seed adsorption was an important factor of seeding machine. The success rate of adsorption would directly affect the success rate and production efficiency of seeding machine. Experimental results showed that the size of suction head had effect on suction success rate when pressure was decided. The suction success rate was high when the diameter of suction head was within 0.6~1.2mm and the vacuum degree was 8kPa. Selecting the diameter of 0.6mm，the success rate reached over 90% when pressure was higher than 6.2kPa for rape seeds and 8.3kPa for cucumber seeds. By orthogonal experiment, it was found that the best adsorption effect was with vacuum degree of 10kPa and diameter of 0.6mm. Compared with manual seeding, the efficiency of seeding machine was improved by 12.9 times. The research provided a new structure and design idea to solve problem in seeding.

Abstract:Under submerged condition, due to the external static pressure at nozzle exit, the cross section and inflow pressure of ejector pipe have significant impact on the suction performance and energy dissipation of annular jet device. In order to better adjust the annular jet nozzle, the methods of numerical simulation and experimental validation were adopted to analyze the impact of different cross section ratios and different inflow pressures on nozzle’s inspiration capacity and gas liquid ratio. From flow field, the energy dissipation and the intensity of vortex were explained for these effects. Results showed that both inspiration capacity and gas liquid ratio were increased in low cross section ratio, but in high cross section ratio inspiration capacity was decreased while gas liquid ratio was increased firstly and then decreased with the increase of inflow pressure, thus the ratio got the maximum value in this case. With the increase of cross section ratio, the inspiration capacity was increased while the gas liquid ratio was decreased. Different inflow pressures had good controllability for the gas liquid ratio with low cross section ratio, meanwhile, different cross section ratios had remarkable controllability for the gas liquid ratio at high inflow pressure. Under the same kinetic energy increment, the turbulent dissipation rate increment at different cross sections was considerably larger than the increment at different inflow pressures, thus the value of energy dissipation at different cross sections was large. All these features had relation to pressure difference between ejection fluid and water in the tank at different inflow pressures and sealing process of ejection fluid for nozzle at different sections.

Abstract:A type of cavitation pattern named triangle cloud cavitation structure, which was formed by tip clearance cavitation, shear layer cavitation and tip leakage vortex cavitation, would cause some adverse effects on its shedding cavity at the trailing edge, such as diminished overall performance and efficiency, rotating instabilities, noise and vibration. Thus the mechanism of the phenomenon should be understood. For the sake of deeply studying the process of cloud cavitation shedding in the tip region of an axial-flow model pump, the filter-based model with modified density of RNG k-ε turbulence model was embedded into the commercial software ANSYS CFX by the secondary development technology for simulation. Simultaneously, the homogenous cavitation model was also adopted to simulate the unsteady cavitating turbulent flows. Some significant results were summarized. The simulation results were compared with experimental values. It could be concluded that the simulation results were agreed well with experimental values by successfully predicting the periodic process of cloud cavitation shedding in the tip region with DCMFBM turbulence model. With the rotation of blade, the shedding cavity was migrated towards the pressure side of neighboring blade and affected the load distribution of the pressure side;meanwhile, it also had impact on its load distribution on the suction side. A radial jet from the hub to the rim was found near the exit of blade, when it reached the blade tip, it eventually impinged on the cavity surface near the wall, which caused the formation of an open cavity with shed bubbly clouds. Then it was entrained into the TLV, forming an unstable and noisy spiraling pattern, which would enhance the instabilities of the flow field in tip region. It was possible that hub vortices characterizing wing-body junctions might have also played a role.

Abstract:In order to research the hydraulic performance of the post position S-shaped shaft outlet conduit under the influence of circulation, the hydraulic performance of the post position S-shaped shaft pumping station under different blade models and different blade angles was simulated with commercial CFD software, and the experiment results were compared with the CFD results. The analysis of hydraulic performance of S-shaped outlet conduct showed that the inner flow field was strongly affected by the residual circulation of guide vane, the coefficient of hydraulic loss was no longer a constant, but a variable which was related to flow field. By comparing the relationship of the average swirl angle in the inlet and the hydraulic loss coefficient of the outlet conduit, it was found that an optimal average swirl angle existed for hydraulic loss coefficient. And the optimal average swirl angle was about 4°~5.3° for two different blades models, and the hydraulic loss coefficient was 1.62×10-4m·s/L. By analyzing the static pressure and total pressure distribution curve, the conclusion below can be drawn: the mainly reason for the hydraulic loss was average swirl angle value at the small discharge, on the contrary the reason for the large hydraulic loss was velocity at large discharge. After the water flowing through the second corner, most of the kinetic energy is recovered. The research result gave a good suggestion for the design and optimization of pump station.

Abstract:Centrifugal pumps are widely used in the solid particles and liquid delivery, a number of areas petrochemical, aerospace, energy, irrigation and the like. When transporting sandy water, its internal wear becomes serious, which affects the life of unit. Therefore, the movement of particles in a centrifugal pump was investigated and the wear characteristics were predicted. Based on the two-phase particle track model and the Tabakoff and Grant erosion model, the simulation of a centrifugal pump was conducted to get the particle track and erosion regulation under different sands or inlet conditions. The result demonstrated that erosion was mostly taken place in hub and pressure side of vane in the impeller compared with shroud and suction side. The particle velocity to pressure side of the vane was increased with the raise of particle diameter, which would lead to dot impact erosion compared with large particles near the inlet side. While the strip scratch erosion was taken place at the press side of the impeller near the outlet when particle diameter was small. Moreover, the position and erosion shape were influenced by particle diameter in significant measure. While the erosion rate density was increased with the increase of concentration and the inlet velocity. Furthermore, the distribution of particle at the inlet also had effect on the erosion state, which meant that with the increase of uniformity of particle in the inlet, the erosion morphology turned into dispersed distribution from continuous sheet.

Abstract:A special testing apparatus was designed for measuring and calculating fluid pressure in pump chamber and balance cavity, fluid pressure in front-back pump chambers was measured and analyzed by changing balance hole diameter and using a pressure sensor. It was found that liquid pressure in back cavity was generally bigger than that in front cavity under normal conditions of seal ring，and the curves of fluid pressure in front-back pump chamber above the diameter of seal ring were different. Based on systematical analysis of pressure curve of pump chamber with or without fluid leakage, the computational formula of fluid pressure in pump chamber with fluid leakage was presented by introducing pressure loss coefficient under the design condition. The fitting formulas of pressure loss coefficient were given by calculation of experimental data under the design condition. Moreover, the theoretical calculation results and the experiment results of fluid pressure in pump chamber with fluid leakage had also been contrasted and analyzed for two centrifugal pumps. The results showed that the computational formula of fluid pressure in pump chamber with fluid leakage had high credibility. Fluid pressure in balance cavity was calculated using mathematics model under the design condition. The experiment results proved that this mathematics model could accurately forecast fluid pressure in pump chamber. In order to control the fluid leakage and reduce the axial thrust, it was proposed that the balance holes diameter of 6~8mm was appropriate through analyzing the theoretical calculation results and experimental results.

Abstract:Gully erosion process researches in recent 60 years were reviewed from the following aspects: definition comparison of gully erosion at home and aboard, critical model for the initiation of gully erosion, influence factors of gully erosion process, prediction model of gully erosion, and gully erosion research methodology. Key research fields were also proposed, including standardization and normalization of gully erosion monitoring;quantification of head ward erosion, sidewall collapsing erosion, and deep cut erosion in gully erosion process;quantification of sediment transport capacity and establishment of sediment transportation continuity equation in ephemeral gully and gully erosion process;soil erosion prediction model at slope scale which included the ephemeral gully erosion, and soil erosion prediction model at watershed scale which covered the gully erosion；methodology research on gully erosion control.

Abstract:At room temperature, dielectric barrier discharge in air can produce non-thermal plasma with atmospheric pressure. Among the existed particles, there must be nitrogen and oxygen free radicals which combined as nitrogen oxides. The technology of non-thermal plasma nitrogen fixation was studied. Nitrogen oxides can be absorbed by water, and the nitrate solution can assist production of nitrogen fertilizer. In previous studies, The effects of time, voltage and frequency on nitrogen fixation were presented, and the subsequent discussion would be shown in this study. To eliminate error of absorption system, nitrogen oxide gas concentration was chosen as experiment detection index. Experimental factors included dielectric materials, dielectric thickness, discharge gap and peak to peak voltage. A four factors and three levels orthogonal experiment design method was used. Through range analysis of the experimental data, it showed that dielectric materials had the biggest effect on nitrogen oxide gas concentration. Through analyzing the average value of each factor, it showed that the optimal level for this experiment was quartz material, 5mm medium thickness, 2mm discharge gap and 30kV peak to peak voltage. Under the optimal level and discharge for 5min, gas concentration of nitrogen oxide was detected as 1004.20mg/m and the efficiency of nitrogen fixation was 2.21g/(kW·h).

Abstract:The depth of flow path of drip irrigation emitter is important geometrical parameter to anti-clogging performance. An Eulerian-Lagrange liquid-solid multiphase turbulence model combined with the kinetic theory of granular flow was used to carry out simulation based on coupled CFD-DEM water-sand two-phase flow in drip irrigation emitter with labyrinth channel. The trajectories and speed of single sediment, speed of sediment group, moving pattern and distribution of sediment group were analyzed. Simulation result indicated that the quantity of sand near the central plane of depth was more than that near the wall. The volume concentration of sediment in channel was increased several times with the decrease of depth. The depth was small;the speed of waterflow in depth direction was descended, but the speed of sediment in depth direction was risen. The average number of hit of each sediment was 14.31 when the depth was 0.6mm, but the number was 2.04 when the depth was 1.4 mm. The increase of impact frequency to wall changed original movement direction of sediment, augmented the number of times of collision between sands and between sand on the wall, which decreased velocity and kinetic energy, and it was difficult for sand to go through labyrinth channel, which caused clogging easily. This method was applied to analyze movement and distribution of sand individuality and group, learn the movement regular from micro-view perspective, and it had become an efficient technique in structure design of labyrinth channel.

Abstract:Pot experiment was conducted to determine the response of vitamin C (VC) content in tomato fruit to soil water condition at different growth stages. Growth stages were divided by the law of tomato development and the growth of the first cluster fruits, including seeding, flowering, fruit early growing, inflation and quality formation stages. Five levels of soil water condition were set at each stage, and quadratic general composite rotatable method with five factors was used. Mathematical model between VC content and soil water content of different stages was established. The main effect, single effect and coupling effect of two factors were analyzed, and model optimization was operated in DPS 3.0. Results showed that the influence of soil water content at quality formation stage on VC content was top-drawer, seeding stage was ranked the second and flowering stage was taken the least. When other stages’ soil water content was (70%~80%)θf , with the increase of soil water content at seeding or flowering stages, VC content in tomato fruit was varied slightly (variable coefficients were 2.46% and 3.08%, respectively), while a downwards parabola change was found when soil water content was risen at other three stages. Additionally, the peaks of parabola were 24.10mg/(100g), 24.21mg/(100g) and 24.10mg/(100g) when soil water contents were (67.79%~77.79%)θf, (65.58%~75.58%)θf and (68.86%~78.86%)θf, respectively. There were significant coupling effects of two factors on tomato VC content, both positive and negative. VC content might reach the highest level of 30.10mg/(100g) when soil water content at five different stages were (50%~60%)θf, (90%~100%)θf, (50%~60%)θf, (80%~90%)θf and (70%~80%)θf, respectively, while yield was decreased sharply. Tomato yield and VC content in fruit acquired desirable level, which were 996.75~1037.99g/plant and 25.40~26.02mg/(100g) when soil water contents at five stages were (90%~99.9%)θf, (90%~99.8%)θf, (90%~99.6%)θf, (74.0%~81.8%)θf and (74.3%~82.5%)θf , respectively.

Abstract:To investigate the effects of installation depths of water-conduct device on root distribution and root growth in dwarf close planting jujube under indirect subsurface drip irrigation (ISDI), three installation depths of water-conduct device were considered in the experiment. The installation depths of water-conduct device were 20cm (T1), 27cm (T2) and 35cm (T3), respectively, with surface drip irrigation (DI) as comparison. Different depths, horizontal distances of jujube roots system distribution were obtained by annular ditch layered methods, the results showed that there were significant differences in jujube roots system distribution under DI and ISDI. On root morphology, root distributions were shallow and horizontal extension under DI. The distribution of root in different soil layers was uniform, and growth direction of root was basically downward under ISDI. ISDI significantly increased the root length density of fine roots (d＜5mm), which increased by 1~2 times than that of DI. Root length density of d>5mm and root system distribution distance in horizontal direction were reduced, and the proportion of fine root length in 20~40cm soil layer was increased. With the increase of depth of water-conduct device, the root length density of fine roots (d＜2mm) was decreased in 0~20cm soil layer and increased gradually in 20~60cm in vertical direction under ISDI. In horizontal direction, the fine root length density of each treatment was comparatively concentrated distribution in 0~20cm soil layer，70% of root was distributed in horizontal range of 0 ~ 20cm, the fine root distribution distance of each treatment was increased. With the increase of depth of water-conduct device, the horizontal distribution distances of roots of different diameter in 0~20cm soil layer tended to be reduced, but that in 20~40cm soil layer tended to be increased. Generally, with the increase of depth of water-conduct device, fine root distribution showed developing trend from shallow and wide to narrow and deep.

Abstract:Rice evapotranspiration and soil evaporation were measured by using canopy mini-lysimeter system in rice growth period in 2015 with water saving irrigation in the South China Plain. The characteristics of diurnal variation in typical days and daily variation during the whole growth period for evapotranspiration (ET), transpiration (T) and evaporation (E) were analyzed. The ratio of E to ET was also discussed. In addition, the correlations between T, as well as E, and related factors at hourly and daily scales were studied based on multiple linear regression method. The results illustrated that the diurnal variations of ET and T were basically consistent, which presented as the singlet trend of inverted “U” shape obviously. At the stage of tillering, E was also varied diurnally in unimodel shape, while there was no obviously diurnal variation after tillering stage. Positive and negative fluctuations of ET at night indicated that the influence of water vapor condensation on measurement of mini-lysimeter cannot be ignored. The daily variation trend of T was also similar to ET, and the two values were increased firstly and then decreased, with peak value occurred at late tillering stage. Moreover, rice evapotranspiration was soil evaporation primarily before late tillering stage, and later transpiration was dominant. The ratio of E to ET was varied from 1 to 0.19 with the growth of rice, and it was increased slightly in the ripening stage with value of 0.23. The main factors that affected transpiration and evaporation of water saving irrigation paddy fields were not identical at hourly and daily temporal scales. Net radiation (Rn) and leaf area index (LAI) were the main influence factors for rice transpiration at hourly and daily scales, respectively, while LAI and vapor pressure difference (D) were the main influence factors for soil evaporation at the two scales, respectively. LAI had significant effect on transpiration and evaporation at both temporal scales (α<0.001), albeit in varying degrees. The analysis of scale difference had important and practical significance to the research of water management and water transformation in the field.

Abstract:The seasonal variations of soil rill erodibility and their potential affecting factors were investigated by carrying out the experiment of water flumes with adjustable bed gradient and using the soil erosion process WEPP model, which was conducted in two tracts of rehabilitated grasslands in “Grain for Green” history during the grass growing season. One (Tract A) had been planted with Leymus secalimus for three years and the other (Tract B) with Medicago sativa L. for 17 years. Results showed that the soil rill erodibility of Tract A of grassland was increased at first and then declined and again increased during the whole growing season （p＞0.05), while the soil rill erodibility of Tract B of grassland was declined at first and then became stable and again declined significantly during the whole growing season （p＜0.05). The soil rill erodibilities of the two grasslands were varied seasonally, which were mainly affected by soil consolidation, formation of water-stable aggregates and root growth. With the increase of soil cohesion, bulk density, content of waterstable aggregates and grass root density, the soil rill erodibility in either soil was declined exponentially. Seasonal variations of soil rill erodibilities of two grasslands could well be simulated with soil bulk density and root density (R≥0.86，NSE≥0.85). The mean soil rill erodibility of Leymus secalimus and Medicago sativa L. during the whole growing season was much less than that of the control tract, which suggested that the practice of “Grain for Green” in hilly regions of the Loess Plateau of China was beneficial to soil and water conservation. The findings of this study may do duty for data support and theoretic basis in elaborating hydrodynamic mechanisms of the soil rill erodibility processes, evaluating effect of grass roots in fields of “Grain for Green” on soil and water conservation, and rationalizing arrangement of soil and water conservation practices and measures in hilly regions of the Loess Plateau of China.

Abstract:Soil erosion responses under different rainfall and runoff patterns are fundamentals for the studies of soil erosion mechanisms. To investigate the influence of flood regimes on soil erosion and sediment yield at small watershed scale, a typical small watershed—Shejiagou catchment was selected to conduct data collection and analysis, and Shejiagou is a first order tributary of Chabagou drainage basin lying in the hilly and gully region of Chinese Loess Plateau. Based on 45 individual flood events recorded at Shejiagou Hydrological Station during 1961 to 1969, all the flood events were categorized into three regimes through a combined approach of K-mean clustering and discriminant analysis with three grouping variables, including flood duration, event flood runoff depth and peak discharge. Regime A was characterized by short duration, small flood runoff depth, low flood variability and medium peak discharge, which was the most common regime. Regime B was featured with medium duration, medium flood runoff depth, medium flood variability and small peak discharge, which was of medium frequency. Regime C mainly included flood events of long duration, large runoff depth, high variability, as well as large peak discharge, which was of the lowest frequency. The regime of flood events was mainly controlled by flood duration at the studied scale. Area-specific sediment yield, mean suspended sediment concentration and maximum suspended sediment concentration driven by different flood regimes can be ranked in the order of C＞B＞A, C＞A＞B, C＞A＞B, respectively. However, no significant difference was found among the three flood regimes for the variables examined (P＞0.1). The runoff-sediment relationship was relatively constant at Shejiagou watershed, the variations in suspended sediment concentration can be well described by the logarithmic function of instantaneous discharge. The sediment output at watershed outlet was mainly controlled by event-based total flood runoff. Given that event flood runoff depth was kept constant, the ratio of area-specific sediment yield driven by different flood regimes (A∶B∶C) was 1∶0.93∶1.22. If the flood duration was increased by 1.7 times, the flood regime-based increase for sediment yield reached the maximum, and the maximum increase rate for area-specific sediment yield was 22%. The results may provide beneficial evidence for categorization of individual flood events, and overall rational-based evaluation on the soil and water conservation benefits brought by runoff regulation systems at watershed scale.

Abstract:In the loess hilly region of China, a large amount of arable land has been replaced by artificial forests, resulting in increased storage of soil organic carbon (SOC). To elucidate the process and mechanisms of SOC sequestration following conversion of cropland to forest, the storage and sequestration rates of SOC associated with sand, silt and clay was measured by physical fractionation on Robinia (Robinia pseudoacacia L.) and Caragana (Caragana korshinskii) lands that have been stood on former cropland for 15~45a. Compared with cropland, the content of carbon in all soil particle-size fractions on all afforested lands was significantly increased with the stand time. Moreover, the highest increase of carbon was in the top soil layer (0~10cm) and similar increase amplitude of carbon was found in 10~60cm soil layers. During the 15~45a afforestation on former cropland, the highest annual sequestration rates of carbon stock in 0~20cm soil depths was in silt, which were 0.21Mg/(hm·a) and 0.11Mg/(hm·a), and similar sequestration rate of carbon was in sand with average value of 0.13Mg/(hm·a) and in clay was 0.06Mg/(hm·a) on Robinia and Caragana lands, respectively. The same changing trend also occurred in 0~60cm soil depth, and sequestration rate of carbon associated with all mineral particles was 1.6 to 2.5 times higher than those in 0~20cm soil depth. Following the annual increase rates, the carbon stocks in sand, silt and clay were varied by 2.6, 1.1 and 0.8 times on Caragana land, and those were varied by 8.3, 2.2, 2.8 times on Robinia land respectively after 45 years conversion of cropland to forest. The average percentage that contributed to accumulation of total SOC in different mineral particles was in the order: silt carbon (51%) > clay carbon (26%) = sand carbon (23%). Additionally, there was a more significant linear correlation between SOC content and carbon management index (CMI) than the linear correlation between SOC content and activity of carbon pool (A). In conclusion, long term stand Robinia on former cropland sequestrated more SOC than stand Robinia in the area. However, carbon in slit was the main fraction for carbon sequestration and carbon in sand showed the fastest turnover rate on both afforested lands.

Abstract:In order to reduce the effect of intensive rainfall on nitrate leaching in summer for greenhouse vegetable field in North Plain China, a three-year (2008—2010) field experiment was conducted in the suburbs of Beijing during the period of intensive rainfall season from July to September. Five different treatments were designed, including three nitrogen fertilizer levels (CK, no nitrogen fertilizer;N1, 380kg/hm and N2, 260kg/hm of nitrogen) in previously grown crop, and two other treatments with and without sweet corn as a catch crop based on the treatments of N1 and N2, denoted by N1C and N2C, respectively. The three-year field observed data was used to calibrate and validate the WHCNS (soil water heat carbon nitrogen simulator) model, and subsequently nitrate leaching, and water and nitrogen balance of different treatments were simulated. The results showed that evaporation and drainage were two main pathways of water consumption for the fallow treatments, while the main pathway of catch crop treatments was evapotranspiration and drainage. The amount of water drainage was in the order of CK>N1≈N2>N1C>N2C. Planting sweet corn can reduce nearly 42% of water drainage compared with without catch crop treatments. The water balance for fallow treatments was positive, and it was negative for the catch crop treatments, which indicated that the sweet corn consumed soil water stored in soil profile. The order of nitrate leaching rate of different treatments was N1>N2>CK>N1C>N2C, and the mass of nitrate leaching for catch crop treatments ranged from 1.3kg/hm to 50.9kg/hm, which was much lower compared with those of N1 and N2 treatments (59.2~273.6kg/hm), and even lower than that of the CK treatment (38.6~151.6kg/hm). The catch crop reduced 80% and 85% of nitrate leaching compared with treatments of N1 and N2, respectively. It can be concluded that using the deep-rooted sweet corn as a catch crop in summer can delay and control the nitrate leaching. Therefore, it can be used as an efficient method to reduce the risk of nitrate leaching for greenhouse vegetable field in the North China Plain.

Abstract:In order to study and illuminate the effects of different raindrops and runoff characteristics on size-selectivity of sediments crumb structure detachment and transportation in soil erosion process, a rainfall simulation study was conducted to examine the sediment particle dynamic distribution characteristics in Beijing, China. Erosion plots (5m×1m) were installed in a 20° hillslope. Experiment treatments included three rainfall intensities (35mm/h, 65mm/h and 100mm/h) of representative rainfalls and three average vegetation coverages (0%, 30% and 80%). The changes of sediment crumb structure at erosion plots with and without raindrop impact were observed through placing the nylon net over the soil surface. The results showed that sediment concentration and soil loss were reduced by 25.91%~31.15% and 35.10%~41.20%, respectively, after eliminating raindrop impact. The sediment mean particle size (D50) of the slope without raindrops was less than that of the slope with raindrops, which was decreased by 23.47%, 27.17% and 31.63% under the three kinds of rainfall intensities. At the initial stage of runoff, coarse sand-size, fine sand-size, fine silt-size and clay-size existed in the form of aggregation, and coarse silt-size was in a state of primary particles. With the extension of rainfall, the E/U (effective-ultimate size) ratio of each graded size was gradually tended to be the value of 1, which indicated sediment particles existed in the form of primary particles. The correlation analysis of the sediment particle size and water flow power under different vegetation coverages showed that the slope erosion process was closely related to the hydrodynamic characteristics. The effect of splash on soil surface accounted for 28.09% of the total detachment degree before the runoff generation, and the soil aggregate fractal dimension increment with no raindrops on the slope was 48.43% of that with raindrops on the slope. In the sediment transport process, sand particles was decomposed into small particles, coarse silt particles were transported as primary particles, and clay particles was gradually enriched in the erosion process. The sediment size-selectivity characteristics by erosion dynamics in the process of erosion were revealed, which deepened the research on erosion regularity of different erosion processes.

Abstract:Rill erosion rate and hydrodynamic parameters present evident spatial and temporal variation characteristics during rill development process on hillslopes. Based on 3D laser scanning technique (LiDAR) and intermittent simulated rainfall experiments, high-precision DEMs were extracted. Temporal and spatial variations of rill erosion and hydrodynamic parameters at different rill development stages on loessial hillslope were analyzed. Results showed that the maximum values of rill erosion rate and hillslope erosion rate occurred at the rill deep cutting dominated stage, while the minimum values of them occurred at the rill headcut dominated stage. Rill erosion rates and hillslope erosion rates were increased at first and then tended to be steady and fluctuated in a certain range with rainfall duration. Hillslope erosion rates reached steady state earlier than rill erosion rates. Rill erosion rates and hillslope erosion rates under 90mm/h rainfall intensity reached steady states earlier than those under 60mm/h rainfall intensity. Rill erosion rates were first increased and then decreased along hillslope and showed parabola trend. The maximum values of rill erosion rate occurred at the hillslope lengths of 6m and 7m. Shear stress, stream power and unit stream power under 90mm/h rainfall intensity were 1.3, 1.1 and 1.4 times as those under 60mm/h rainfall intensity. Hydrodynamic parameters of overland flow and rill flow showed different variation trends with the increase of rainfall duration. Shear stress, stream power and unit stream power were increased with fluctuations of unit slope length under two rainfall intensities. It showed strong positive linear correlation between rill erosion per unit width and three hydrodynamic parameters. The critical values of shear stress, stream power and unit stream power reached the maximum values at initial phase of rill development.

Abstract:In order to exactly figure out the climate characteristics and its relationship with soil water content, precipitation and air temperature characteristics were analyzed by using the standardized precipitation index (SPI) and the standardized precipitation evapotranspiration index (SPEI) as well as Mann-Kendall tests based on precipitation and air temperature data from Wuqi synoptic station over the period of 1957—2014, and regression analysis of soil water content was also performed. The results showed that: (1) an obvious difference was existed among annual precipitations, and the seasonal precipitation series had different trends. On the whole, precipitation displayed a decreasing trend with value of 11.17mm/(10a). Compared with precipitation, significantly increasing trend of air temperature was detected at seasonal scale with a rate of 0.01℃/(10a). Significantly changing trends existed in the series of precipitation and air temperature, and the crossing points were 1972 and 1991, respectively. (2) Both SPI and SPEI can accurately reflect the climate characteristics of the study area. In general, wet year alternated with dry year during the period of 1957—2014. The main rainy period was estimated to appear in the 1960s. The occurred chances for wet years and dry years were almost the same, but both of them were far less than normal years. Wuqi county initially exhibited a warming and drying trend, which would be even more serious in future. (3) The relationship between soil water content in 0～1m soil depth on the slopes of different directions and one month scale SPI/SPEI could be stated with a quadratic function which had high fitting accuracy. SPI-1/SPEI-1 must achieve a certain degree then showed positive correlation with soil water content, and different slopes had different required levels. This research showed that both SPI and SPEI were suitable for application in loess region of northern Shaanxi because of the similar analysis results. This method can be applied to other different parts of the climate change research, especially in arid and semi-arid region;the results can provide reference for climate change in loess region of northern Shaanxi, and provide theoretical basis for promoting vegetation restoration artificially.

Abstract:In order to provide technical basis for prevention of desertification grassland in agro-pastoral ecotone in Siziwang banner, Inner Mongolia, the in-situ test was adopted to study the blown sand movement laws and explore the mechanism and protection effect of soil wind erosion for degraded grassland with 20% coverage, repaired grassland with 40% coverage of Caragana korshinskili gapped belt scheme plantation and 60% coverage of Agropyron mongolicum randomly distributed plantation, the movable wind erosion tunnel and its supplement equipment were used. The results indicated that, at the same wind speed in the wind tunel, the descending order of soil surface roughness was C. korshinskili grassland, A. mongolicum grassland and degraded grassland. The average roughness of C. korshinskili grassland was 2.46cm, which was 1.95 times of A. mongolicum grassland and 2.76 times of degraded grassland. With the decrease of height from the ground, all the wind speeds of three grasslands were decreased, and when wind speed was 9m/s in wind tunnel, wind velocities at height of 8cm were reduced by 82.23%, 66.67% and 61.11% for C. korshinskili grassland, A. mongolicum grassland and degraded grassland compared with those at height of 64cm, respectively. The sand transport rate of C. korshinskili grassland was the smallest, and the sand transport rate curves of A. mongolicum grassland and degraded grassland were decayed in the form of exponential function along with the increase of height from ground, and the curve of degraded grassland was decayed faster. Whereas, the sand transport rate curve of C. korshinskili grassland had a maximum value at its top of 30cm, and it was exponentially decayed under its top. Therefore, the C. korshinskili grassland had significant effects on obstructing and changing wind-sand flow, and it could still achieve good anti-erosion effect at low vegetation coverage.

Abstract:Based on the hydrological process, several factors affecting the mean soil infiltration rate (im) under the individual rainfall event were determined, which were the slope gradient (S), slope length (L), rainfall intensity (Ri), rainfall amount (Rain), vegetation cover of the land surface (Vc), antecedent soil water content (Asw) and fractal dimension of soil particle (D). Using the data obtained from the field runoff-plot under natural rainfall events, the quantitative relationships between im and the seven factors were analyzed, and the multi-parameter estimation model for im was established by means of multivariate nonlinear regression method and BP neural network model. Relationship between im and S was in accord with quadratic parabola, and im was firstly increased and then decreased with increase of S. The im was increased linearly with the increase of L and Ri, it was increased with the increase of Rain by power function and linearly decreased with increase of D. Hyperbolic functions were obtained between im and Vc, Asw, and the im was increased with increase of Vc and decreased with increase of Asw. On the strength of the seven functional relationships, the estimation model of im was built by multivariate nonlinear regression method. The relative error of around 72% data was within ±10%. Using the seven factors as input parameters, a BP neural network model for prediction of im was established. The best training algorithm was Levenberg-Marquardt method and the ideal neurons nodes of the hidden layer were determined as 15 by the grey relational degree method. The relative error of around 81% data was within ±10%.

Abstract:Crop water requirement is one of the most important factors in farmland water circulatory system, its accurate estimates could help with crop irrigation management. The ability of simulating evapotranspiration (ET) for CSM-CERES-Wheat model is very important, which determines the accuracy of model output parameters. The objective was to evaluate the capability of CSM-CERES-Wheat model to simulate the cumulative evapotranspiration, daily evapotranspiration and soil water content of winter wheat (Triticum aestivum L.) in 2011—2012 and 2012—2013 growing seasons under semiarid condition. The daily ET was measured by using weighing lysimeter that installed in the experimental plot. The ability of CSM-CERES-Wheat model by using two different ET calculating approaches, i.e., Priestley-Taylor (PT) and Penman-Monteith (PM), and the simulation results were evaluated and compared. Data were obtained from two experiments with three irrigation levels that were conducted under controlled condition in a rain-out shelter in Yanling, Shaanxi Province of China during the 2011—2012 and 2012—2013 growing seasons. Results showed that the simulated cumulative ET, daily ET and soil water content of CSM-CERES-Wheat model with both PT and PM approaches had great agreement with measured values, and the simulated cumulative ET and daily ET were 5.4% and 3.4% less than those of observed values, respectively. The CSM-CERES-Wheat model simulated cumulative ET for winter wheat in two growing seasons through PT approach was less than that through PM approach, the relative difference between two approaches was ranged from -3.11% to -0.05%. The model could simulate soil water content correctly as well, in the depth of 0~20cm soil layer, the RMSEn between simulated results based on two ET approaches and observed values was 39.38%, which was relatively high and not good, but below the 20cm soil depth, the RMSEn between simulation results that based on two ET approaches and observed values was less than 23.1%, and the simulation results in depth of 40~60cm soil layer got the best agreement with the observed values. The model with both PT and PM approaches simulated the above-ground biomass and grain yield accurately as well. The RMSEn of final above-ground biomass for two growing seasons were 13.57% for PT approach and 22.76% for PM approach, and RMSEn of grain yield were 11.80% for PT approach and 15.42% for PM approach, both of the simulated results had good agreement with observed values. The model using PT approach provided smaller ET and higher soil water content than those derived from PM approach as compared with measured data. Additionally, the model using PT approach provided higher final above-ground biomass and grain yield than those derived from PM approach as compared with measured data. However, the model with both two approaches could simulate the total above-ground biomass and grain yield with RMSEn within 25% of measured data. Overall, it can be concluded that the CSM-CERES-Wheat model using the two different approaches, i.e., PT and PM, was able to accurately simulate winter wheat ET and soil water content. The results also confirmed that the model could be applied in arid and semi-arid areas, and it can be used as a tool for agricultural water management and supplying the decision support for winter wheat growth in Guanzhong Plain.

Abstract:According to the difference in the degree of difficulty or easiness of decomposition, the soil organic carbon can be divided into readily oxidizable organic carbon and hardly oxidizable organic carbon. The readily oxidizable organic carbon plays an important role in supplying ability of soil nutrient, while hardly oxidizable organic carbon contributes to stabilizing the soil structure, and it is related to the storage of soil organic carbon. Meanwhile, soil carbon pool management index (CPMI) can reflect the effects of external condition on soil organic carbon contents and active organic carbon contents, and comprehensively reflect the extent of decline or update of soil quality. However, there is little information on the effect of chicken manure co-applied with inorganic fertilizer on soil organic carbon oxidation stability and CPMI, especially the study of kidney bean/maize rotation soil was scarcely reported. Therefore, for exploring the effect of chicken manure co-applied with nitrogen fertilizer in different proportions on soil organic carbon oxidation stability and CPMI in kidney bean/maize rotation soil, a field experiment, including four treatments, i.e., N100 (100% of nitrogen was provided by urea), M10N90 (10% and 90% of nitrogen was provided by chicken manure and urea, respectively), M30N70 (30% and 70% of nitrogen was provided by chicken manure and urea, respectively), and M50N50 (50% and 50% of nitrogen was provided by chicken manure and urea, respectively) were carried out. The aim was to determine the effects of different treatments on total organic carbon (TOC), microbial biomass carbon (MBC), readily oxidizable carbon (ROC) contents, organic carbon oxidation stability, as well as CPMI of kidney bean/maize rotation soil during the 2009—2014 period. Results indicated that the TOC contents of M10N90, M30N70 and M50N50 treatments were increased by 5.21%, 12.74% and 19.87% in comparison with the N100 treatment, respectively. The MBC and ROC contents and CPMI achieved the highest value in M30N70 treatment and had significant differences with other treatments, which showed 54.03%, 16.50% and 10.43% increases in ROC content and 75.10, 30.75 and 27.94 increases in CPMI, respectively, compared with those in treatments of N100, M10N90 and M50N50. However, the oxidation stability index of organic carbon in M30N70 treatment was obviously lower than other treatments, which was reduced by 35.95% compared with N100 treatment. Furthermore, the M30N70 treatment could significantly increase yield and improve quality of kidney bean, which had statistically significant differences with other treatments. Correlation analysis revealed that yield and Vc content of kidney bean were significantly or extremely significantly correlated with microbial biomass carbon, readily oxidizable carbon, organic carbon oxidation stability and carbon pool management index in the soil, indicating close inner link among each indicator. In conclusion, the application of chicken manure co-applied with inorganic fertilizer, especially the M30N70 treatment, was beneficial to soil quality amelioration and soil nutrient-supply capacity improvement as well as growth of high-yield and high-quality kidney bean in the rotation plantation.

Abstract:The effects of biochar which was made of crop straw on physical properties of meadow black soil and dynamic changes of soil water after individual rainfall were studied. The experiments were conducted by field pilots which were located at the sloping farm-land with three degrees of land slope gradient of Hongxing State Farm, Heilongjiang Province in 2015, and soybean, the main crop type of study area, was selected as experimental crop. Five levels of biochar were set, as 0t/hm, 25t/hm, 50t/hm, 75t/hm and 100t/hm of biochar were put in the field pilots, which were represented by CK, C1, C2, C3 and C4, respectively. During the whole growth period of soybean, the soil physicochemical properties were investigated, including soil water characteristic curve, soil water diffusivity, soil bulk density, rate of soil porosity, organic matter content of soil, saturated soil water content, field water capacity and characteristics of soil water after individual rainfall. Soil water characteristic curve was measured by centrifuge, soil water diffusivity was tested by horizontal vitreous soil column, and soil water contents were measured by TDR field soil water measurement system in situ. The results showed that biochar could remarkably reduce soil bulk density and decrease soil water diffusivity of meadow black soil in the black soil area. The residual soil water content could be declined by 27.6% by treatment of C4. With the increase of biochar quantitative level, soil water diffusivities of C1, C2, C3 and C4 were decreased by 34.8%, 37.5%, 71.4% and 58.9%, respectively. Additionally, it could give a rise to the saturated soil water content, field capacity and soybean yield, and the treatment with 75t/hm biochar got the highest yield. During an individual rainfall, with the use of biochar, the variation amplitude of soil water content tended to fall. This helped to accelerate the process of soil water content changing from rapid declining stage to slow declining stage, meanwhile, it increased the soil water content in the slow declining stage obviously. The research results can provide theoretical foundation for efficient utilization and protection of soil and water resources in agriculture in the black soil region.

Abstract:The treatment of anaerobic digestion effluent has become the bottleneck of large-scale biogas station application in China. In order to promote the engineering application of ammonia nitrogen stripping and recovery of anaerobic digestion, an integrated equipment for ammonia stripping and recovery with relative low cost was designed and constructed on-site to demonstrate its efficiency in real biogas plants, decrease lime dosage and control foam. This device mainly consisted of three functional units: pretreatment unit, pH value adjustment unit and ammonia stripping and recovery unit. To reduce the energy consumption, economical reflux circulated stripping method was adopted. A pilot test was carried out by using swine manure anaerobic-digested effluent at a biogas station of Beijing suburbs, the results showed that pH value of anaerobic digestion can be reached 10.5 by adding 22g lime per liter after four months experiment and optimization, and ammonia removal rate reached 55.8% when the temperature and gas-liquid ratio were 30.7℃ and 960, respectively. Although adding dry lime powder was easily operated, the dissolved efficiency was relatively low. Pre-dissolved lime slurry can effectively avoid the defects and reduce the dosage by 7.5g/L. Moreover, the effective calcium oxide content of lime from different producers had significant differences. And the performance of lime from different producers in increasing anaerobic digestion effluent pH value was compared and the lime dosage was also analyzed at different temperatures. Finally, higher ammonia removal rate could be attained by using this integrated device under ambient temperature and low air-liquid ratio (0～1000).

Abstract:The influence of calcium-based catalyst/absorbent on hydrogen production of corn stalk pyrolysis-gasification was investigated in a two-stage fixed-bed biomass pyrolysis-gasification system. the results showed that addition of CaO could in-situ absorb CO2 generated from the gasification process, thus enhanced the gasification process to form more H2. As the pyrolysis/gasification temperature was 650°C, mass ratio of steam to biomass (S/B) was 2, and molar ratio of CaO to C was 1, compared with the trail without CaO addition, H2 concentration in the product gas was increased greatly from 28.7% to 56.2%, H2 yield was increased from 64.3 mL/g to 195.8mL/g, while CO2 concentration was decreased sharply from 21.5% to 1.1%. CaCO3 could be found in the used absorbent after gasification, which further proved the enhancing effect of CaO addition. Moreover, the enhancing effect of CO2 absorption of CaO was closely related to the gasification temperature. High H2 concentration and yield could be obtained with gasification temperature in the range of 600℃ to 700℃ from the pyrolysis-gasification of corn stalk. As gasification temperature higher than 700℃, the CO2 absorption capability of CaO was weakened, CaO mainly acted as a catalyst during the gasification process. The introduction of active NiO to CaO absorbent could decrease the content of small molecular hydrocarbon gases in the product gas, and increase the H2 concentration and yield. With NiO loading of 10% on CaO, H2 concentration in product gas could achieve 63.7%, while H2 yield was close to double of that with CaO addition, which reached 341.3mL/g.

Abstract:The five pyrolyzing furnaces which adopted grading heating technology was developed to solve the problem of bad control of temperature in the process of biomass pyrolysis. Combining with continuous conveying principle, circulating water cooling technology, secondary cracking technology of pyrolysis gas, secondary condensing collection of bio-oil and biogas, the equipment for biomass continuous grading pyrolysis was developed. Each furnace was heated by a 3kW electric wire with PID control allowing a wide range of heating rates and a maximum temperature of 700℃. Pyrolysis test which used the crushing corn straw was completed after the pellet equipment was made, results showed that the equipment worked well and the feed throughput can be up to 12kg/h, the yield of carbon was 29.97%, the low calorific value was 26.21MJ/kg, the yield of fix-carbon was 55.63% and the temperature of collected carbon was 24℃ when the temperature of furnace was set at 550℃, 600℃, 600℃, 600℃ and 550℃, respectively, after separation of pyrolysis gas and bio-oil, the pyrolysis gas flow into an afterburner chamber where enough air fuelled ensured complete combustion, which conformed to the demand of grading heating and continuous pyrolysis.

Abstract:Unclear puffing power has always been an important problem for instant pressure drop puffing process using superheated vapor. And the condensation water produced by superheated vapor is absorbed by the food material before puffing, which possibly makes bad effect on puffing ratio．A general mathematical model of puffing power was established．Results indicated that puffing energy was produced by flash evaporation of superheated water from internal material and instant release of superheated vapor．Besides，porosity of sample varied with different sample moisture contents and condensation water generated in thermal transfer process before puffing．Thus，puffing ratio was related to the sample moisture content，porosity and status of superheated vapor．Using Granny Smith green apple slice as experimental objects，results suggested that porosity of sample was significantly decreased with the increase of sample moisture content．At temperature of 430～470K，pressure of 0.1～0.5MPa and apple moisture content of 15%～35%，the established puffing power model could effectively predict and evaluate the relationship between puffing condition and puffing ratio (R＞0.89)．High vapor pressure had insignificant influence on condensation water，and distinctively elevated the energy of superheated water and superheated vapor，which resulted in the biggest puffing ratio．High temperature of superheated vapor can only strengthen superheated water energy，but significant increase of condensation water mass led to superheated vapor energy reduction，and it had slight effects on puffing energy improvement and puffing effect．Moreover，high moisture content of sample significantly increased superheated water energy，but condensation water reduced superheated vapor energy，which generally showed great effects on improvement of puffing power and puffing ratio．The research results illustrated the power mechanism of instant pressure drop puffing process using superheated vapor，which would be helpful to further study on the control of puffing ratio.

Abstract:Ginger oil nano-emulsions was prepared by using the method of ultrasonic emulsification with OSA starch PG Purity Gum 2000 (PG) and Hi-Cap 100 (HC) as emulsifier. The microstructure, rheological characteristic, antimicrobial ability and storage stability of the ginger oil nano-emulsions were studied. The TEM micrographs of emulsions showed that the microstructure was improved by preparing nanoemulsions with ultrasonic emulsification and PG or HC. Steady-shear scanning results showed that ginger oil nanoemulsions were a kind of typical shear thinned rheological fluid and had Newtonian fluid characteristics. Frequency scanning results showed that ginger oil nanoemulsion had viscoelasticity. Nanoembedding systems had no significant influence on the antibacterial ability. PG ginger oil nanoemulsion and HC ginger oil nanoemulsion both had good antimicrobial ability, but the antimicrobial ability of PG ginger oil nanoemulsion was better than that of HC ginger oil nanoemulsion. During the storage of 28d at 4℃, 25℃, 55℃, PG and HC ginger oil nanoemulsions both showed good physical stability on average particle size and Zeta potential. Both the PG and HC ginger oil nano-emulsions had over 80% retention of the gingerol, which was the main pungent compound of ginger oil. Among the five main volatile compounds, α-curcumene and α-zingiberene had no significant change (p>0.05) during the storage. β-bisabolene and β-sesquiphellandrene had no significant change during storage at 4℃ (p>0.05). PG ginger oil nano-emulsion had better storage stability than HC ginger oil nano-emulsion. Storage at 4℃ was more suitable for PG and HC ginger oil nano-emulsions than storage at 25℃ and 55℃. This study would provide technical support for the application of ginger oil nano-emulsions in food industry.

Abstract:Thermogravimetry (TG) and derivative thermogravimetry (DTG) were used to investigate the thermal oxidative properties of six normal vegetable oils. The influence of different heating programs on the weight changing curves was studied and the onset oxidation temperature (Ton) and peak oxidation temperature (Tp) were located from the DTG curves. Through the application of Ozawa-Flynn-Wall iso-conventional method, the oxidation kinetic properties of oils were deduced and the correlation between thermal behaviors and triacylglycerol composition was analyzed. The results showed that both Ton and Tp were increased with the raise of heating rate and Tp was varied more sensitively, which indicated that the reactions occurred around Tp could be more acuminous to the change in surroundings. Varying degrees of correlation were found between thermal behaviors and triacylglycerol distribution: Ton and Ea(Ton) were found to be positively correlated with high saturated triacylglycerols but negatively correlated with high unsaturated ones. Similar results were found between Tp, Ea(Tp) and various components but with weaker correlations. Specific correlation was depended on the type of fatty acid chains on glycerol skeletons. Thus, predictions of oil thermal stability could be done according to thetriacylglycerol profiles. Thermogravimetry analysis was praised for trace sample size, fast operation and high sensitivity, which would show promising prospect in oil processing and quality control.

Abstract:To understand the influence of different proteins and their additive amounts on permittivities of milk, and to explore a method for detecting the adulteration of milk protein, the open-ended coaxial-line probe technology was used to study the influence of frequency (20~4500MHz) and protein additive amounts (0~4.70%) of different proteins, including whey protein, soybean protein and tripolycyanamide, on permittivities (dielectric constant ε′ and dielectric loss factor ε″) of milk, and the influence mechanism of different proteins and their additive amounts on permittivities were analyzed. The results showed that over the frequency range of 20~4500MHz, ε′ was decreased with the increase of frequency, and ε″ decreased firstly and then increased with the increasing frequency. The minimum value of ε″ observed at around 2000MHz. With the same protein additive amount, the milk added with soybean protein had the largest ε′, while the milk added with tripolycyanamide had the smallest ε′. ε″ of the milk added with whey protein and soybean protein were higher than the values of milk with tripolycyanamide at the same protein additive amount. The permittivity values (ε′ and ε″) of milk were increased linearly with the increase of additive amounts of soybean and whey protein, and all the linear correlation coefficients were greater than 0.92. However, the correlation between the permittivities values and tripolycyanamide content was not obvious, and all the linear correlation coefficients were less than 0.51. The study results indicated that different proteins and their additive amounts had different influence on dielectric properties of milk, which made it possible to identify the different protein types and their additive amounts in milk based on dielectric properties.

Abstract:Musalais is a very traditional Uygur ethnic characteristic drink and the co-existence of Saccharomyces cerevisiae and lactic acid bacteria (LAB) is widely presented in the natural fermentation process. Five LAB mediums were used for isolating from two Musalais samples and semi-quantitative assay was performed to examine the biofilm formation of the LAB strains. The positive-biofilm LAB was performed to mixed-cultivate with five Saccharomyces cerevisiae from Musalais. The effects of co-cultured with Saccharomyces cerevisiae on LAB growth and biofilm formation were explored and the effects of five Saccharomyces cerevisiae by the mixed biofilm formation on the ethanol fermentation were detected under the simulation conditions of Musalais natural fermentation. The results showed that 21 suspected LAB strains were isolated from two Musalais samples and two strains were detected as strongly positive biofilm formation (OD490nm>0.56). The further identification results showed that the two strains were Lactobacillus plantarum (T1-8) and Pediococcus pentosaceus (M1-6), respectively. After co-culturing, the Saccharomyces cerevisiae A had a very significant effect on the biofilm formation of the L.plantarum (T1-8) （p＜0.01) and the Saccharomyces cerevisiae B and D had significant effects on the biofilm formation of the L.plantarum (T1-8) （p＜0.05). However, all the Saccharomyces cerevisiae had no obvious effects on growth and biofilm formation of P.pentosaceus (M1-6). The ethanol yields of the corresponding Saccharomyces cerevisiae were improved nearly twice as much or more in the groups of A+T1-8, B+T1-8, C+T1-8, D+T1-8, B+M1-6, C+M1-6 and D+M1-6. The other groups also had different degrees of increase.

Abstract:To realize the chlorophyll content inversion with hyperspectral technology for apple leaves, the spectral data and SPAD values were obtained by SVC HR-1024i full band spectrometer and SPAD-502 portable chlorophyll analyzer, respectively. The correlation of original spectral data, the first derivative spectral data and measured SPAD values were analyzed, various spectral parameters were selected based on the sensitive wave bands and models between spectral parameters and measured SPAD values were established. The original spectra and the SPAD value were significantly negatively correlated in visible bands, and significantly positively correlated in NIR bands. The first order derivations of spectra and the SPAD value were negatively correlated in blue and green light bands, and positively correlated in yellow and red light bands. The SPAD inversion model based on NDVI and R565 fitted well. The first derivative spectral data and measured SPAD values had improved correlation coefficient compared with the original spectral data, and the determination coefficient R in the inspection process of models establishment based on normalized difference vegetation index (NDVI) and R565 were 0.8896 and 0.8524, which showed better prediction ability than other models. To avoid the difference of order of magnitude, the spectral parameters and measured SPAD values were normalized, and polynomial regression and support vector regression (SVR) were carried out by using the normalized spectral parameters and SPAD values. The R in the modeling process and inspection process of SVR inversion model were 0.7410 and 0.8914 with root mean square error of 0.1332 and 0.1256, respectively, which indicated that the SVR inversion had high precision and good prediction ability. Compared with polynomial regression, the SVR algorithm had better inversion effect, thus it can be used as an optimization algorithm for chlorophyll content inversion.

Abstract:In order to provide three dimensional (3D) models with complete agronomic information and high fidelity for the construction of digital maize system, a 3D template resource library of maize organs was constructed. Firstly, maize plants were subdivided into basic structural units, including nodal root, lateral root, mesocotyl, stems, sheath, leaf, tassel and ear. Secondly, the data acquisition standard of major maize organs was established from the perspective of 3D data acquisition by analyzing the morphological and structural features of the organs. 3D data of the maize organs were acquired by using 3D scanners and 3D digitizers according to the standard, and geometric models of the maize organs were constructed on the basis of the measured 3D data. Finally, the 3D template resource library of maize organs was constructed by assembling these geometric models. The library took cultivar, organ name, growth period etc. as its key words for resource retrieval. It contained a large number of maize organ models of different cultivars and multiple growth periods with consistent agronomic parameters. The construction of the library would promote the digital maize system and played a great role in the research, production, promotion and demonstration of maize industry, it also provided a reference for the 3D resource library construction of other plants.

Abstract:In order to improve the accuracy of forest above-ground biomass estimation， constructed from modeling factor selection and modeling aspects, a PSO-LSSVM biomass estimation method was proposed by considering comprehensive of the image texture features, topographical features, spectral features. Selecting Songshan Nature Reserve as study area, with the data sources from ZY-3 satellite remote sensing image, the measured data of 194 survey plots, forest resource inventory data, and the digital elevation model data, the Pearson correlation relationship was analyzed between 46 feature variables and forest above-ground biomass. With the optimal feature extraction variables chosen, the PSO-LSSVM model was established in Matlab 2014a. The determination coefficient (R) and root mean square error (RMSE) were taken for comparative analysis of the accuracy of PSO-LSSVM model and multiple linear regression model. The results showed that the prediction accuracies (R) of PSO-LSSVM model in coniferous forest, broadleaf forest and shrub were 0.867, 0.853 and 0.842, which were improved by 23.15%, 19.13% and 14.40% compared with the multiple linear regression model, respectively. The PSO-LSSVM model had self-study ability and adaptive capability, it can replace the traditional traversal optimization method, and it had great advantages on global optimization and convergence rate with small sample volume requirement and high precision accuracy.

Abstract:Multiple cropping is an efficient way to improve the crop yield for Guanzhong area of Chinese Loess Plateau. The spatiotemporal pattern change of multiple cropping in Guanzhong area from 2000 to 2013 was investigated. Cropping index was employed to quantitatively assess the multiple cropping. The twi-difference algorithm was applied to estimate the cropping index based on the crop NDVI time-series reconstructed from 250m 16d MODIS NDVI datasets with the iterative Savitzky-Golay method. Results were as follows: the cropping index was shown to be the highest in Xi’an City and it was decreased with the increase of distance from the city;the croplands with double seasons were mainly located in the Weihe River plain with an altitude of less than 600m;the single-season croplands were primarily distributed over the loess ravine regions of the northern Guanzhong area, Qinling mountain area of the southern Guanzhong area and alluvial plain along the Yellow River (eastern Guanzhong area). The cropping index in 2000—2013 was found to reveal a two-stage downward trend. During 2000—2005, the cropping index was reduced very slowly and the rate of the decline was less than 2%;however, the decrease rate became high during 2006—2013 which reached 15.7% in 2013. The development of urbanization and economical agriculture were demonstrated to significantly influence the decline of cropping index. Through the comparison with the statistics issued by the government, the average relative error of cropping index estimated from MODIS datasets was between 0.3% and 15.1% at the regional level, and the result also had an accuracy of 93.7% at the pixel level. The presented results provided useful and reliable information for the decision making on spatially-targeted local agricultural planning.

Abstract:The problem of effective feeding for swimming fishes in recirculating aquaculture system (RAS) was studied. In order to solve this problem, a novel assessing method for the feeding activity of shoal was proposed with the help of tilapia which was used as the experimental objective, and the proposed method was based on the improved kinetic energy model. Instead of the complex segmentation of foreground of shoal and the tracking of individuals among shoals, the change characteristics of reflective areas of water surface caused by feeding activity of shoal were regarded directly as the key factor in this method. Firstly, the reflective areas of water surface were segmented and extracted in HSV-based color space. Then, with the help of the Lucas-Kanade optical flow, statistics method and entropy, the disorder degree of the change in reflective areas was calculated and analyzed. Finally, combined with information of the changing magnitude of reflection areas, the intensity assessment of feeding activity of shoal was executed. According to the comparison and analysis of the experimental results, the proposed method showed good description in intensity of feeding activity of shoal with different digesta index of stomach and bowels (20.35±10, 150.61±10) under strategy of over-satiation feeding through intermittent feeding at intervals of (40±2) s.

Abstract:In order to explore an energy-efficient thermal environment control model in greenhouse, the application of thermal environment phase change control system was studied in solar greenhouse. A solar greenhouse root zone thermal environment control system was designed and built, including the phase change thermal unit, latent heat storage and exchange unit, root temperature control unit, circulation pump group and circulation pipeline. The latent functionally thermal fluid was used as liquid heat transferring medium in the heat collection, delivery and release of solar radiation. The system included three different work modes, and the thermal performance testing project was formulated. In winter of 2014, the operation performance of the designed system and application effect on lettuce seedlings were tested through controlled experiment of three different operation conditions, using two greenhouse models with the same construction and root zone thermal environment control system. The results indicated that the designed system significantly reduced the indoor air and shallow substrate temperature fluctuations in experimental greenhouse model, and significantly lowered the everyday highest indoor temperature and obviously increased root zone temperature of root zone substrates in winter, thus improving balance of temperature distribution among substrate layers with different depths. During the whole winner test process, the everyday highest indoor air temperature and the average fluctuation range of air temperature were averagely decreased by 7.2% and 5.1%, respectively, and the average 20cm depth root zone temperature and the average fluctuation range were increased by 15.1% and 39.0%, respectively. Among the three operation stages, system performances of the stage with flow rate of 3~4L/min was the optimum one, with the most obvious increases of average temperature and average fluctuation range of 20cm deep substrate, as well as the most significant rise in reduction percentages of temperature differences between 5cm deep and 20cm deep substrates. In addition, the plant height, stem diameter, leaf area per plant and width of maximum leaf of lettuce seedlings in the model were increased by 13.4%, 11.9%, 79.1% and 35.3%, respectively. Overall, the effect of the system was remarkable in sunny days. In conclusion, the phase change heat collecting system can effectively control the air the root zone thermal environment in greenhouse and promote seedling growth of vegetables.

Abstract:In order to harvest the vibration energy of suspension and make it with failsafe characteristics, a hybrid suspension structure with spring, damper and linear motor in parallel was proposed. According to the dead zone in the harvesting process of linear motor, a DC/DC boost circuit was designed so that the electromagnetic damping force can still be provided by the linear motor in the process of dead zone. Based on the energy dissipation of traditional passive suspension, an explicit expression of energy efficiency in the same driving cycle was obtained. And the energy efficiency of suspension was used as evaluation index of suspension. Meanwhile, to take into account of the performance of system dynamics, the influence of damping value on energy regeneration performance and vibration isolation performance was studied, and the optimal shock absorber damping value was determined by compromise design. A hybrid energy regenerative suspension dynamic model was established, the vibration isolation performance and energy regeneration performance of suspension based on optimal damping of vibration damper were compared and analyzed. The simulation results showed that the hybrid energy regenerative suspension can effectively coordinate the energy efficiency and vibration isolation of the vehicle. Finally, based on the simulation, the experimental study on hybrid energy regenerative suspension was carried out on the INSTRON 8800 numerical control hydraulic servo exciting test bench. The test results were in agreement with the simulation results, which verified the correctness of simulation results.

Abstract:It is important to enhance mobility performance of the Mars rover wheel in soft terrain. The didactyl foot, which is the key part of ostrich foot possessing the excellent running ability on sand, was regarded as the bionic prototype. According to the principle of engineering bionic, the wheel with bionic drum shaped surface moving on sand with high mobility performance was designed. A kind of Mars soil stimulants was selected as experimental material. The wheel-soil bin test system was adopted to test the tractive trafficability of ordinary drum shaped surface wheel and bionic drum shaped surface wheel. The rut morphology, drawbar pull and sinkage were regarded as evaluation indicators. Results showed that when the slip-rotation ratio was over 0.85, the rut accumulation phenomenon of ordinary drum shaped wheel was more serious than that of bionic drum shaped wheel. Under the same experimental conditions, when slip-rotation ratio was less than 0.42, the drawbar pull of ordinary drum shaped wheel was slightly larger than that of the bionic drum shaped wheel. When the slip-rotation ratio was over 0.42, the drawbar pull of the bionic drum shaped wheel was superior to the ordinary drum shaped wheel. The maximum drawbar pulls of bionic drum shaped wheel and ordinary drum shaped wheel were 11.6N and 2.6N, respectively. The slip-rotation ratio had small influence on sinkage of the ordinary drum shaped wheel, and the value of sinkage was about 35mm. However, the sinkage of bionic drum shaped wheel was increased with the increase of slip-rotation ratio. This research provided a design way for enhancing the mobility performance of the Mars rover in soft terrain.

Abstract:In order to explore the process of liquid film formed by fuel droplet impact on the surface in small-size combustor of diesel engine, a numerical model was developed using coupled level set and volume of fluid method, including heat transfer and contact resistance, to explore the mechanism of a droplet impacting on inclined surface. The dynamic motion and mechanism of flow and breakup of droplet were obtained according to results analysis. The effect of impacting velocity on spreading factor, average wall heat flux, forward and backward spreading factors and spreading velocities were also explored. The results showed that the liquid jet was observed only at the front spreading edge during the oblique impact, which was different from the horizontal impact. The tangential forces for the oblique impact promoted the forward spreading and the formation of liquid jet at the front spreading edge. The breakup of liquid jet was observed at both neck and root areas. The pressure gradient inside the liquid jet was the main factor resulting in the formation, development and breakup of the liquid jet;capillary wave resulted in the breakup at the neck and root of liquid jet. The impacting characteristics were closely related to impacting velocity, the spreading factor, average wall heat flux, forward and backward spreading factors and spreading velocities obviously increased with the increase of impacting velocity;the effect of impacting velocity on impacting characteristics decreased as impacting velocity increase.

Abstract:Cloud manufacturing is a new service-oriented intelligent manufacturing model, which contains plentiful knowledge to support service system operating, and the manufacturing resources and capabilities are shared (as services) through the internet. However, there is a lack of in-depth research in knowledge cloud capability service, influence factors and its evaluation approach. The comprehensive evaluation system of the whole features was established for knowledge cloud capability service, and a new quantificational knowledge cloud capability evaluation approach was presented based on cloud reasoning. The expected value and hyper entropy of knowledge capability cloud were used to evaluate the satisfaction of service performance by cloud processing the evaluation indicators, and a cloud reasoning controller was designed to depict the satisfaction change style of knowledge capability, which provided support for the intelligent shared service of manufacturing resources and capability in cloud manufacturing system, e.g. design as a service, simulation as a service, production as a service, assembling as a service, and testing as a service. The result of simulating experiments showed that the validity and effectiveness of the presented approach provided beneficial exploration for evaluating knowledge cloud capability service of cloud manufacturing.

Abstract:Gas flow valves are widely used in pneumatic field. The technology of valves, such as butterfly valves and ball valves, combined with valve positioner mode is mature, and the prices are reasonable. But there are some disadvantages like nonlinear relationship between the opening degree of the valve and flow area, low positioning accuracy, lack of repeatability and so on. A new rotary flat flow valve with linear characteristics was proposed. The nominal diameter was 50 mm. With good repeatability, it can overcome the above disadvantages on the whole. It can achieve the linear regulation of flow from 0% to 95%. A special shaped curve was designed for the valve plate to achieve the linear relationship. And a decelerating stepper motor was used to drive the valve plate to ensure the accuracy and repeatability of valve. It can also quickly adjust the valve plate to any position. The function of the curve of valve plate was deduced with cut-and-fill method. Then a special plane-rotation seal structure was proposed to ensure the plate seal. The computational fluid dynamics method was employed to simulate the internal fluid field of the valve at different opening positions. Finally, detailed simulation and experimental study were carefully carried out to verify the design and performance of valve. Both theoretical calculations and experiment results showed that the linear correlation coefficient was greater than 0.99. Experiment results at different positions showed that the flow repeatability of the valve was better than 0.26%. Although the performance of the new structure valve had been verified, the reliability of the special seal and working lifetime of the rotary flat valve were pending to be proved in the future work.

Abstract:In order to lay a certain foundation for optimization of mechanical structure vibration reduction, the viscoelastic damping material optimal layout was studied. Damping materials dosage was restricted to realize structural lightweight design. Based on the Hamilton variation principle and the deformation displacement relationship of damping structure, structure vibration differential equation was deduced. A topological optimization mathematical model for constrained damping structure that used structure maximum damping ratio as the optimization goal, structure damping materials consumption as constraint condition, structure damping element status as design variables was built. To search structure topological optimization iteration direction, the modal damping ratio of sensitivity was derived. The constrained damping element adding and deleting criterion was presented, the program for constrained damping structure was established, and independent mesh filter method was adopted to avoid the checkerboard. The bi-directional evolutionary structural optimization (BESO) can improve the utilization efficiency of damping materials, thus BESO was used to optimize the damping structure. After evolutionary structural optimization(ESO) for damping structure, the increases of the first and the third order damping ratios were 54.51% and 36.21%, respectively, while after BESO for damping structure, the increases were 76.69% and 58.36%, respectively, and the phenomenon of checkerboard was improved, the damping material layout was consistent with structural strain energy figure. To verify the result of topology optimization for damping layout, harmonic response analysis was carried out on the constrained layer damping structure, the simulation results showed that the structural response amplitude was low and vibration suppression effect was good by means of BESO method.

Abstract:R141b and Al2O3 were selected as base fluid and nanoparticle, respectively, and the two-step method was used to prepare Al2O3-R141b nanorefrigerant. The mass fractions were 0.2%, 0.5% and 0.8%, respectively. The flow boiling heat transfer of Al2O3-R141b nanorefrigerant and R141b refrigerant in rectangular microchannels with hydraulic diameter of 1.33mm was experimentally investigated. Experimental conditions included saturation pressure of 176kPa，inlet subcooling from 6℃ to 12℃，volume flow rate from 20L/h to 50L/h，and heat flux from 11.1kW/m to 26.6kW/m. The experimental results were used to evaluate seven heat transfer models for pure working fluid and two heat transfer models for nanorefrigerant. Results showed that the pure working fluid heat transfer models were not suitable for nanorefrigerant. The Peng-Ding heat transfer model for nanorefrigerant combined with the Kim-Mudawar model for pure working fluid gave relatively good agreement with experimental data, the mean absolute error (MAE) was 17.22%, which reflected the effect of nanoparticles on flow boiling heat transfer. A new nanoparticle impact factor (the ratio of heat transfer coefficient of nanorefrigerant to refrigarant) correlation was proposed based on Peng-Ding model and experimental data, the new correlation had good predictability with MAE of 15.2%, and the new correlation combined with the Bertsch model provided good prediction of heat transfer coefficient for nanorefrigerant in microchannels, and the MAE was decreased to 16.4%.

Abstract:The dynamic behavior and its optimization of a planar 3-link biped robot under randomly uncertain disturbance were investigated. Based on the biped kinematic model and hybrid dynamic model under ideal situation, the control objective function and HZD (Hybrid zero dynamics) feedback control were firstly established, from which the biped state parameters were optimized with the energy consumption function, and the robotic stable walking under the ideal situation was achieved. Secondly, the biped kinematic model and hybrid dynamic model under the randomly uncertain disturbance were established, from which the robotic dynamic behavior controlled by the HZD feedback control method was investigated under the randomly uncertain disturbance. Finally, taking the randomly uncertain disturbance into account, the disturbance compensator integrated into the HZD feedback control was constructed based on a back propagation neural network, and a novel BPNN-HZD (Back propagation neural network-hybrid zero dynamics) feedback control method was proposed to optimize the biped dynamic behavior. The dynamic simulation results and the stick figures showed that the planar 3-link biped robot would gradually appear divergent dynamic behavior if the randomly uncertain disturbance could not be well compensated, while the BPNN-HZD feedback control can effectively weaken the randomly uncertain disturbance effect on the dynamical response of robot, and the biped divergent dynamic behavior would be avoided.

Abstract:The parallel manipulator with three-dimension translation and one-dimension rotation (in short, 3T1R) has wide requirements in processing technology, such as high-speed catch, positioning assembly, transportation. A novel 3T1R parallel manipulator was presented based on the theory of position and orientation characteristics (in short, POC). A complete type synthesis of parallel manipulator that can perform 3T1R motion was made based on the theory of POC. Then, one topology was selected from the different possibilities of parallel manipulators after imposing some practical requirements. The selected parallel manipulator was composed of four identical arms and a single platform, and the composite parallelogram structure in each arm brought in better limb stiffness. The parallel manipulator had characteristics of full symmetry, fold ability, good stiffness, large work space, and so on. In addition, the forward and inverse displacement equations of the parallel manipulator were derived, which had great importance when implemented in velocity control. The inverse position equation had 16 solutions at most, and the forward position equation only had 8 solutions at most. Finally, the solution algorithm of the forward displacement equations was given, and a numerical example was provided to confirm the efficiency of the solution procedure. The research results had a reference value for follow-up studies of the new manipulator and its application.

Abstract:Based on the theory of POC and ordered single-opened-chain, a design method for structural synthesis of lower-mobility non-overconstrained parallel mechanisms (PMs) was proposed according to the over-constraint characteristics of independent loops. Firstly, the relationships between POC of mobile platform, POC of kinematic limbs and the number of independent displacement equations of independent loops were analyzed. The existence condition of lower-mobility non-overconstrained PMs was obtained, and the universal method and step for structural synthesis were further proposed. Secondly, the non-overconstrained PMs can be classified into three types of configurations according to different combinations of kinematic limbs and their corresponding constraints on the platform, which showed that the non-overconstrained PMs composed with different types of kinematic limbs had different performances. Finally, the rules of possible kinematic limbs and their assembly modes were illustrated by comparative analysis with a few examples. The research results enriched the analysis theory and methods of non-overconstrained PMs, and laied the foundation for type selection and applications of lower-mobility non-overconstrained PMs.

Abstract:The parallel mechanism with position and orientation characteristics limb (POL) is a kind of special low mobility mechanism which consists of 2~5 identical active unconstrained limbs and a passive POL. The motion characteristics of the mechanism are determined by POL, thus it was referred to as motion constraint generator by some literatures. This parallel mechanism with POL has many excellent characteristics, such as high rigidity, high control accuracy and bearing capacity, and the synthesis process is simpler than the other mechanism. Firstly, principle of composition of parallel mechanism with POL was proposed, and some formula of topological structure characteristics were simplified, including its position and orientation characteristics equation (POC), degree of freedom (DOF) and coupling degree, meanwhile, synthesis process of topological structure was listed. Secondly, topological structures of POL with 2~5 DOF and unconstrained active limbs were synthesized according to POC theory. Type synthesis of 4-DOF parallel mechanism was used as an example to illuminate the principles and methods of designing this kind of mechanism. In this section, the concept of generalized POL is mentioned, which contained not only traditional precisely constrained passive chains, but also some active branched chains. Thirdly, the mechanism was classified on the basis of the number of driving pairs in POL, and several cases were designed of each type. Lastly, two ways of structure optimization for chain structure and mechanism symmetric were presented to improve mechanical properties of partial examples. The research provided a more systemic theory and design methodology for topological structure synthesis of the parallel mechanism with POL than previous literatures.

Abstract:Development and practical application for practical parallel mechanisms still have a long way to go, the reason is that the topological structure characteristics of the mechanisms are to be revealed. The purpose of topological structure characteristics analysis is to provide criteria for optimization and performance assessment of parallel mechanisms. Using topology structure theory for parallel mechanism based on position and orientation characteristics (POC) and the ordered single-open-chain (SOC), the topology characteristics of six practical and useful parallel mechanisms were analyzed, and three main topological structure characteristics, including the POC set, degree of freedom (DOF) and coupling degree were uncovered. Analysis for topological structure characteristics was an effective method to reveal the structure composition and the topological structure characteristics of mechanisms. The best structural decomposition route can be achieved with the concept of “coupling degree”, the complexity caused for forward kinematic analysis of the mechanisms can be reduced and the forward position solutions of mechanisms can be analyzed efficiently. These characteristics reflected the basic performance of the topological structure, kinematics and dynamics of these mechanisms, which provided theoretical foundation for the optimization of topological structure, kinematics and dynamics as well as application. Topological structural analysis of practical parallel mechanisms can provide comparable schemes for innovative mechanism designs. This work also revealed some general rules which can be beneficial to the design and application for any other parallel mechanisms.

Abstract:The generalization of spherical rectification theory was considered to spatial RCCC linkages to visit four given positions. The problem of synthesis of spatial four-bar linkages of the RCCC type for rigid-body guidance with four given positions was focused, in which R denoting a revolute, C denoting a cylindrical kinematic pair. While synthesis equations for CC and RC dyads were available in literatures, the synthesis of spatial RCCC four-bar linkages required special attention due to its asymmetric topology. However, infinitely many exact solutions to the problem of CC-dyad synthesis existed for the four-pose rigid-body-guidance problem, the RC-dyad synthesis admitted only approximate solutions, thus the RCCC linkage was capable of visiting four positions. A solution region theory was proposed to synthesis a RCCC linkage which was to visit four positions. Firstly, the expression of spherical Burmester curve and the classification was given to make a solution region. The second solution region (moment solution region) was born follow-up by picking a point on Burmenster curve solution region. Secondly, the second region which also was the spatial 4C linkage solution region, while the linkage was 2-DOF. Through restricting the prismatic joint between drive and ground on spatial 4C linkage solution region, a spatial RCCC linkage which can visit four given positions was got. Finally, two examples were given which proved that the theory was validated and correct.

Abstract:In order to launch the lunar soil sampling test, a novel parallel mechanism of three degrees of freedom was designed and analyzed for the position and orientation adjustment. According to characteristics in movement of the mechanism, the freedom degree of mechanism was calculated by the modified K-G (Kutzbach-Grübler) formula after the analysis and calculation, the mechanism has a total of 3 degrees of freedom with 2 rotation and vertical movement, and the inverse solution of the kinematics problem was solved by adopting the closed vector method. The evaluation indexes of performance in velocity, acceleration and dexterity of the mechanism were established. A multi-objective genetic algorithm was proposed to optimize the structural parameters of the mechanism based on the performance of velocity and dexterity. The working space and singularity as well as performance in velocity and dexterity of the mechanism could be obtained after analyzing the optimized structural parameters. Results showed that the performance in velocity was excellent under the condition that α and β of the moving platform were moved in the range of -0.35~0.35rad and the maximum value of the velocity performance index of the sampling test mechanism will appear in this range. The results also showed that the singularity would not appear when the performance indexes in dexterity were in the range of [4,5] and the mechanism had good movement performance and the operation velocity of the attitude of the moving platform in the characteristic direction and be satisfied. All the analysis results proved that the mechanism can meet the requirements of lunar soil sampling test and it had certain reference value for development of lunar soil sampling test.