Using Biogas Slurry to Regulate Growth,Field and Fruit Quality of Greenhouse Tomato and Nitrogen Dynamics in Root Zone北大核心CSCD

【Objective】The physiological development of tomato is affected by a number of integrative abiotic and biotic factors and the purpose of this paper is to investigate how irrigation with biogas slurry alerts the yield and fruit quality of greenhouse tomato.【Method】The experiment was conducted in a greenhouse from autumn in 2017 to spring in 2018 by irrigating the tomato with a mixture of fresh water and biogas slurry at volumetric ratio of 1∶8, 1∶6 and 1∶4 at flowering stage and fruit-elongation stage respectively. In each treatment, we measured growth, yield, and fruit quality of the tomato, as well as the dynamics of total nitrogen in the root zone. 【Result】The tomato growth was positively related to the biogas slurry ratio at significant level, and the 1∶6 and 1∶4 ratio gave the highest total dry matter at the flowering stage and the fruit expansion stage respectively. The 1∶6 treatment gave the best return, and compared to CK (without biogas slurry), it increased the return by 12.93% in autumn and 12.31% in spring respectively. Irrigating with 1∶4 ratio at fruit elongation stage gave the highest yield, and compared to CK, it increased the yield by 26.59% in autumn and 27.71% in spring respectively. The 1∶4 treatment gave 4.32% increase in yield compared to chemical fertilizer application in spring. T5 and T6 treatments improved soluble sugar and solid, as well as and sugar-acid ratio, while T2 and T3 treatments increased titratable acid and vitamin C content.【Conclusion】Irrigation by mixing biogas slurry and freshwater at 1∶6 and 1∶4 volumetric ratio at flowering-fruiting stage and fruit expansion stage can considerably improve yield and quality of tomato. © 2019 Authors. All rights reserved.     

Characteristics of soil organic carbon andtotal nitrogen storages for differentland-use types in Central Yunnan Plateau

Two-factor analysis of variance and redundancy analysis were used to analyze the characte-ristics of soil organic carbon and total nitrogen storage in garden land, forestland, grassland, farmland, and bare land in the Dachunhe watershed of Jinning District, Kunming City, Yunnan Province, China. The effects of the soil organic carbon and total nitrogen stratification ratio and soil physical and chemical factors on the storage characteristics of organic carbon and total nitrogen of different land-use types were analyzed. The results showed that the rates of carbon and nitrogen stratification in soil from 0-20 cm and 40-60 cm of the same land-use types differed were statistically significant(P& lt; 0.05). The organic carbon and total nitrogen stratification ratio SR1 of garden land soil was 38.5% and 25.3%, respectively, higher than SR2. The soil organic carbon and total nitrogen stratification ratio SR2 of diffe-rent land-use types are greater than SR1. There were statistically significant differences in the SR2 soil organic carbon and total nitrogen stratification ratios(P& lt; 0.05). Soil organic carbon and total nitrogen storage of different land-use types gradually decreases with increasing soil depth, with the maximum soil organic carbon and total nitrogen storage in the 0-20 cm soil layer. Soil organic carbon and total nitrogen storage at the same soil depth were significantly different(P& lt; 0.05). Soil organic carbon and total nitrogen storage in the garden land were greater than those in the other land-use types. Soil orga-nic carbon and total nitrogen storage in 0-20 cm garden land were 4.96 and 3.19 times those in bare land, respectively; soil organic carbon and total nitrogen storage were explained by 93.66% and 1.53% in redundancy analysis RDA1 and RDA2, respectively. All physicochemical factors except Available Phosphorus and pH were statistically significance with carbon and nitrogen storage(P& lt; 0.05). Soil ca-tionic exchange capacity, Available Phosphorus, C/N ratio, and Moisture Content were positively correlated with organic carbon and total nitrogen storage. In contrast, soil Bulk Density was negatively correlated with organic carbon storage and total nitrogen; soil cation exchange capacity. Available Phosphorus, C/N ratio, and Moisture Content were the main factors promoting soil organic carbon and total nitrogen accumulation.     

Efficacy of Fertilization in Improving Soil Aggregation,Carbon and Nitrogen in Soil Reclaimed from Subsided Areas Caused by Coal Mining北大核心CSCD

【Objective】The objective of this paper is to present experimental results on efficacy of fertilization in improving aggregation and carbon and nitrogen accumulation in soil reclaimed from subsided areas caused by coal mining.【Method】The experiment was conducted under conventional irrigation with non-fertilization as the CK. We compared three treatments: applying organic fertilizer, inorganic fertilizer, and mixture of organic and inorganic fertilizer. For each treatment, we measured the size of soil aggregates, and carbon and nitrogen content in 0~20 cm and 20~40 cm soil in a coal mining-induced subsided area at Jincheng City in Shanxi Province.【Result】Compared to CK, organic fertilizer significantly increased the content of macro-aggregates sized >1 mm, and reduced the content of micro-aggregates sized < 0.25 mm. Inorganic fertilization enhanced formation of micro-aggregates, compared to organic fertilization. Applying organic fertilizer significantly increased the average weight diameter (MWD) and geometric mean diameter (GMD) of the aggregates, and reduced the fractal dimension D of the aggregates. The content of organic carbon and total nitrogen in soil under organic fertilization was the highest, followed by organic-inorganic fertilization. The content of carbon and total nitrogen in soil with a single application of inorganic fertilizer was much lower than that under organic fertilization. Majority of organic carbon and total nitrogen were found in aggregates > 0.2 mm, 1～2 mm and 0.25～1 mm, especially under organic and organic-inorganic fertilization. The C∶N ratio in all aggregates (except those in 0.053～0.25 mm) was much lower under organic and organic-inorganic fertilization than under CK, and C∶N ratio in CK and inorganic fertilization was comparable.【Conclusion】Fertilizations, especially organic fertilizer, can enhance macro-aggregation in reclaimed soil from subsided areas induced by coal mining. It also increased the content of organic carbon and total nitrogen in the aggregates. © 2019 Authors. All rights reserved.     

Physical and Chemical Properties of Soil at Southeastern Edge of Anabasis salsa in Junggar Basin北大核心CSCD

【Objective】Soil is heterogenous and its physical and chemical properties vary spatiotemporally. The purpose of this paper is to present the results of an experimental study on the physical and chemical properties of soil in Anabasis salsa in Gobi region at the southeastern edge of Junggar basin.【Method】We measured organic matter, total phosphorus, total nitrogen, electrical conductivity, pH and water content in soil at locations 5 cm and 10 cm from the center of shrubs, and 20 cm from the outer edge of shrubs.【Result】In horizonal direction, there was no significant difference in organic matter, total nitrogen, total phosphorus, electrical conductivity, pH and water content in the 0~50 cm soil at all locations. In vertical direction, the organic matter and total phosphorus in the proximity of the Anabasis salsa decreased monotonically along the soil profile, while the total nitrogen increased first with the depth followed by a decrease. Both electrical conductivity and pH increased with depth, and soil moisture peaked somewhere within the soil profile.【Conclusion】Our results showed that the physical and chemical properties of soil in Anabasis salsa did not show significant change in lateral direction but varied erratically in the vertical direction. © 2019 Authors. All rights reserved.     

Spatial Variability of Soil Moisture at Different Scales in Sandy Loam in Northern Henan Province北大核心CSCD

[Objective]Soil moisture plays an important role in ecosystem function and hydrological processes. This paper investigated the hieratical distribution of soil moisture at different scales over a maize field.[Method] The studied site was a 50 m×50 m plot at the Experiment Station of Chinese Academy of Agricultural Sciences in Xinxiang, Henan province. We measured soil moisture in 0~100 cm soil from 36 locations at 10 m×10 m and 2 m×2 m scale, respectively.[Result]Geostatistical analysis revealed that the soil moisture was normally distributed and its confidence level at every scale was higher than that of logarithmic normal distribution. The value of the confidence level decreased as the sampling scale increased, and the difference between average soil moisture content at fine scale and moderate scale was smaller than the difference between moderate scale and large scale. In general, the confidence interval, standard deviation and coefficient of variation of the soil moisture increased with sampling scale. At large scale, the semi-variance function increased with lag distance, while at small and moderate scale, the variation function appeared to be independent of the lag distance. To achieve the same confidence level and accuracy in estimating soil moisture, the number of samples needed to be taken from the field increased with sampling scale. We also found that in estimating soil moisture, the number of samples needed to be taken depended on the required accuracy more than on the confidence level.[Conclusion]The probabilistic distribution and statistical characteristics of soil moisture in the field was scale-dependent. In estimating soil moisture, the number of sampled taken from the field needs to consider the scales to which the measured data will be applied. © The Author(s) 2019.     

Mean Velocity Measuring Point of Semi-circular Open Channel Section Based on Flow Partitioning Theory北大核心CSCD

【Objective】The purpose of this paper is to reveal the characteristic position of the mean velocity along the normal line of the semi-circular channel wall and provided a novel method for flow measurement in non-uniformed channel, the physical model experiments were conducted in semi-circular channel.【Method】Based on the measuring results of flow velocity under different hydraulic conditions, the theoretical formula for calculating the mean velocity characteristic position along the normal line of the semi-circular channel wall was derived from flow partitioning theory. Considering the influence from side wall to friction velocity, the mean flow velocity of the entire semi-circular channel section can be obtained by measuring the flow velocity at the characteristic location.【Results】This paper proposed the theoretical formula and the measurements achieved a good agreement within 10% error. The formula can clearly reflect the distribution of the semi-circular open channel well. The velocity distribution should be analyzed along the normal line,thus the analysis methods was more reasonable. 【Conclusion】The theoretical results on determining mean velocity characteristic position fitted well the results from experiment and it indicated the formula has higher precision. The flow velocity at a specific position can be measured to further estimate the mean flow velocity of the section, so as to quickly and accurately determine the flow rate of the channel section in the project. © 2019 Journal of Irrigation and Drainage. All rights reserved.     

Effects of Biochar for Abating Salt Stress and Promoting Seeding Growth of Winter Wheat in a Saline Soil北大核心CSCD

The surface soil of the Yellow River Delta is rich in salt, which makes the soil salinized, compact and barren. The salinization hazard with NaCl as the main component directly affects the quality of coastal soil. Adding biochar to saline-alkali farmland can improve soil properties and promote crop growth.【Objective】The purpose of this paper is to clarify the changes of soil salt ions and winter wheat seedling growth after adding biochar to saline soil.【Method】A field experiment was conducted to investigate the effects of low dose (0~4 g/kg) of Reed carbon on soil salt ions, potassium-sodium ratio in wheat seedlings, potassium utilization efficiency and seedling biomass.【Result】The application of biochar could reduce the salt ions in soil solution, increased the potassium-sodium ratio in the winter wheat seedlings and the potassium use efficiency of the wheat seedlings, and increased the seedling biomass of winter wheat; The salt reduction and the incremental effect under the addition of 4 g/kg biochar use was the most obvious. Compared with CK, the Na+ in soil solution decreased by 9.43%, the K/Na and potassium use efficiency of seedlings increased by 56.80% and 25.48%, respectively, and the biomass of wheat seedling increased by 15.72%.【Conclusion】Biochar application can promote the increase of biomass by holding Na+ in soil solution and increasing K/Na and potassium utilization of winter wheat seedlings. The research can provide a theoretical basis for the process mechanism of biochar for salt reduction and fertilization, increase efficiency and increase yield, and provide preliminary guidance for the feasibility of biochar for salinized soil improvement. © 2019 Office of Journal of Irrigation and Drainage, Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences. All rights reserved.     

Quantitative visualization of Taylor-Couette flow with helical protrusion using optical and ultrasound imaging method

The simplified flow of drilling process in the soil hardening or oil rig site was experimentally investigated. Two flow models were used in this study. One is the concentric cylinders with helical protrusion at the inner cylinder. The other is the concentric plain wall cylinders with axial flow. The ra dius ratio and aspect ratio of both models are the same with 065 and 48, respectively. The mud is the typical fluid seen in the soil hardening processes. We used not only the water and but also the mud for the working fluid in this study. We used the optical PIV for the water flow measurement and echo PIV for the mud flow. In case of the water study, the dominant vortical structures appeared in both the protrusion and plain model with axial flow. In case of mud flow, the vortices shown in the water model disappeared and the push and pull up motion by the protrusion is dominant. We believe this information can be useful to understand the flow physics of drilling process in the complex fluid flow.     

Pressure pulsation in stages ofelectric submersible pump at shut-off under various speeds

Electric submersible pumps were widely used in agricultural fields, petroleum and various other industries. The pressure pulsation caused fatigue failure due to vibration in electric submersible pump and affects the life and performance of its system. The objective of this study was to experimentally investigate the characteristics of pressure pulsation which were generated at various stages of a multistage electric submersible pump during closed valve operation at different speeds. An electric submersible pump with five stages was selected for conducting experiments. A variable frequency drive(VFD)was used to operate the electric submersible pump at five different speed settings from 40 to 60 Hz. Piezoresistive pressure transducers were mounted at each stage of the electric submersible pump to capture the unsteady pressure signals. At each speed setting, the electric submersible pump was operated at the shut-off condition and the signals of unsteady pressure from all the five stages were captured. A fast fourier transformation(FFT)was carried out on the pressure signals to convert into frequency domain. From the spectra of pressure pulsation signals, the characteristics of pressure pulsation are obtained for each stage and for various speed settings which are then used to understand its variation with speed and stages.     

Sensitivity Analysis of the Reference Evapotranspiration in Ebinur Lake Oasis北大核心CSCD

【Objective】The evapotranspiration of crop depends on many factors and this paper analyzed its sensitivity to various meteorological factors in Ebinur lake oasis.【Method】Monthly ET0 in Ebinur lake oasis was calculated using the Penman-Monteith formula based on meteorological data measured from 1962 to 2016 at four meteorological stations in the region. The sensitivity of ET0 to the highest and lowest temperature, relative humidity, sunshine duration and wind speed was calculated using sensitivity analysis; and the possible existence of any trends in the ET0 was analyzed using the MK trend test. We also calculated the variation of the sensitivity coefficient for each site.【Result】The MK trend test revealed that the evapotranspiration, sunshine duration and wind speed in the region have been in decline, while the highest and lowest temperature and the relative humidity have been in rise. Analysis found that the ET0 was sensitive to meteorological factor in an order of relative humidity > the highest temperature > wind speed > the lowest temperature > sunshine duration. The sensitivity coefficient of ET0 to different meteorological factors varies spatially, with the coefficients for the highest and lowest temperature, wind speed and relative humidity being high at Alashan pass-way in northern Ebinur lake, and low at Wenquan station. Wenquan station had longer sunshine duration than Alashan pass-way.【Conclusion】ET0 is most sensitive to relative humidity in Ebinur lake oasis, and least sensitive to sunshine duration. © 2019 Authors. All rights reserved.     

Multi-factor Analysis of the Effective Precipitation for Crops in Semi-arid Region北大核心CSCD

【Objective】The purpose of this paper is to present a method to estimate the effective precipitation for crops in arid region.【Method】The model considered precipitation, soil and crop, and it was based on four modules: canopy interception, soil water tolerance, surface runoff, precipitation and deep percolation. The results calculated by the model were compared to those calculated from water balance using the data measured from the field. We applied the model to calculate spatiotemporal distribution of the effective precipitation for crops in five counties in Hebei plain.【Result】①The coefficient of determination (R2) and Nash-Sutcliffe efficiency (NSE) in all results were above 0.85, proving the reliability of the model. ②The effective precipitation for growing season of the wheat-maize in the five counties was 400.03 mm, and the infiltration coefficient of precipitation was 0.84. In wet, normal and dry year, the effective precipitation for crops was 419, 454 and 355 mm respectively, and infiltration coefficient of precipitation was 0.76, 0.86 and 0.83 respectively. The effective precipitation for crops in Luancheng and Yuanshi was higher than that for other counties.【Conclusion】The proposed model was reliable for estimating effective precipitation for crops at large scale in semi-arid region. © 2019 Authors. All rights reserved.     

Retrieving Soil Moisture Using Spectral Mixture Analysis of Landsat8 and the Moderate Resolution Imaging Spectroradiometer北大核心CSCD

【Objective】Soil moisture plays a critical role in many hydrological and ecological processes and understanding its spatiotemporal changes is imperative to ecosystem management and irrigation design. This paper presents and tests a method to estimate soil moisture distribution using satellite technologies.【Method】We took Guangli Irrigation District at Jiaozuo in Henan Province as our study area. The Landsat-8 and MODIS imageries from the area were used to retrieve soil moisture with the apparent thermal inertia and vegetation water supply index, respectively. Using the abundance of vegetation and soil moisture decomposed by the spectral mixture analysis as weighting factors, we retrieved the soil moisture distribution in the area using the two methods.【Result】The correlation coefficient between the measured soil moisture and the retrieved using the vegetation water supply index method and the apparent thermal inertia method was 0.47 and 0.51 respectively. We found that combining the two methods could improve the correlation coefficient between the measured and retrieved soil moisture to 0.73. 【Conclusion】Our results showed that the proposed method is reliable and can adequately estimate soil moisture in irrigation district grown with a diverse of crops. © 2019 Authors. All rights reserved.     

Responsive Change in Groundwater Table in Karst to Precipitation and Yellow River in Pingyin County北大核心CSCD

【Objective】This paper aims to unravel the relationship between groundwater table fluctuation in karst and the precipitation and water level of the Yellow River at Pingyin in Shandong province.【Method】The analysis was based on data measured from groundwater in two karsts in the proximity of the Yellow River, precipitation and change in water level in the river from 2007 to 2018. The response of groundwater table fluctuation to precipitation and water level in the Yellow River was calculated using cross- correlation analysis, continuous wavelet transform and cross- wavelet transform.【Result】Both precipitation and groundwater table fluctuation had a 12- month period. The responsive change in groundwater table lagged behind the precipitation by 1~8 months, and the water level in the Yellow River by 0~10 months. The precipitation and groundwater table oscillated with a period of 0.86~1.20 a and 0.86~1.36 a respectively, while the oscillation period of the Yellow River water was 1 a and 3 a. The average velocity at which water flowed from the Yellow River to the karst was 21.62~ 25.53 m/d.【Conclusion】The responsive change in groundwater table in the karst in Pingyin to water level in the Yellow River was slightly slower than to precipitation. © 2019 Authors. All rights reserved.     

Effects of Waterlogging on Morphology and Chlorophyll Fluorescence Characteristics of Cherry Tomato at Seedling Stage北大核心CSCD

【Objective】The aim of this study was to investigate the responses of cherry tomato to waterlogging at seedling stage, and to provide reference for waterlogging resistance cultivation of off-season cherry tomato in the tropical area.【Method】Five different varieties of cherry tomatoes were used as materials in pot culture experiment, with soil waterlogging treatment and normal moisture treatment as the control (CK). The morphological characteristics indexes of shoot and root and chlorophyll fluorescence parameters in leaves of cherry tomato were measured in different days of waterlogging. And the effects of waterlogging on morphological characteristics and chlorophyll fluorescence parameters at seedling stage of cherry tomato were analyzed.【Result】Results showed that waterlogging significantly decreased the plant height, stem diameter, leaf area, leaf number and SPAD value of cherry tomato, but had no significant effect on leaf thickness. The root diameter of cherry tomato had no significant affects, but the root volume was significantly increased in HongFei 6 and TaiwanZanMei during waterlogging. Compared with CK, the root length and root surface area of HongFei 6 increased significantly, while that of QianXi decreased significantly during waterlogging. Additionally, waterlogging increased the initial fluorescence (Fo) and non-photochemical quenching coefficient (NPQ), and significantly decreased the maximum photochemical efficiency (Fv/Fm), apparent electron transfer rate (ETR) and photochemical quenching coefficient (qP) of cherry tomato leaves, besides HongFei 6.【Conclusion】The results above indicated that during waterlogging the growth and development and chlorophyll fluorescence in leaves of cherry tomato were seriously affected, but there had different effects among five different varieties . Among five varieties of cherry tomatoes, the strongest waterlogging resistance was HongFei 6, while the weakest waterlogging resistance was QianXi. © 2019 Journal of Irrigation and Drainage. All rights reserved.     

Optimal Design of Vortex Pump Using Approximate Model and the Non-dominated Sorting Genetic Algorithm北大核心CSCD

【Objective】The cavity width L, blade width b2 and the number of blades Z are the most important geometric parameters affecting the performance of vortex pump. This paper aims to present a method to optimize the vortex pump. 【Method】The study was based on approximate model and the non-dominated sorting genetic algorithm II (NSGA-II), in which the pump cavity length, blade width and the number of blades were calculated using the central composite design of DoE (design of experiment). The performance of the designed pump was examined using CFD, and the effect of L, b2 and Z on vortex pump efficiency and shear stress on the blade wall was calculated using the Kriging model. The NSGA-II was used to optimize the geometric parameters.【Result】The optimal parameters calculated from the methods were L=25 mm, Z=8, b2=26.45 mm.【Conclusion】We proved that CFD and NSGA-II can be used in a combination to calculate the optimal parameters of the vortex pump, and they can significantly improve efficiency of the pump and reduce the shear stress on the blade. Our results revealed that the optimization can reduce the width of the non-blade cavity by 16.67%, and increase the number of blades of the impeller and the outlet width of the blade by 1 and 25.95% respectively. At the design flow rate, the optimal design increased pump efficiency by 1.06% and reduced the average shear stress on the blade from 274.37 Pa to 204.57 Pa. The optimal design made the shear stress on the blade more uniform, in addition to reducing the shear stress on the outlet of the blade. © 2019 Authors. All rights reserved.     

Autumn Irrigation Alerted the Geochemistry of Groundwater in Hetao Irrigation District：Take Yichang Irrigation District as an Example北大核心CSCD

【Objective】Surface infiltration could change biogeochemical reactions in groundwater thereby alerting its chemical compositions. The aim of this paper is to investigate the responsive change in chemical composition of groundwater to infiltration following the autumn irrigation in irrigation districts.【Method】The experiment was conducted in Hetao Irrigation District, during which we measured the change in concentration of Na+, K+, Ca2+, Mg2+, SO42-, Cl-, HCO3- and CO32- and then statistically analyzed them.【Result】The irrigation increased the concentration of Cl-, SO42-, KNa, Mg2 and HCO3-, but slightly reduced the concentration of Ca2+. The TDS was higher in south and lower in north of the irrigation district. The Piper diagram showed that the Cl-Na was the dominant groundwater type, accounted for 75% and 61% of the studied area before and after the irrigation respectively. Irrigation turned groundwater in 16.7% of the studied area to Mg-SO4-Cl type. The Gibbs model and ion proportional coefficient diagram revealed that the chemistry of groundwater in the studied region was mediated by evaporation, weathering and leaching of silicate and evaporite, and is independent of precipitation. 【Conclusion】The mean TDS in the groundwater increased by 32.9% after the autumn irrigation, indicating the impact of soil leaching. Improving drainage after the autumn irrigation is hence essential. © 2019 Journal of Irrigation and Drainage. All rights reserved.     

Computational fluid dynamics of left ventricular assist device under unsteady flow

Left ventricular assist device (LVAD) in this study is a mechanical tool that is used to support blood flow in the patient with heart disease. It supports left ventricle by building up the pressure to the pump outlet connected to the aorta. This pump was designed based on the magnetic driven centrifugal pump with a unique small washout hole constructed inside the impeller to generate the washout flow passage to prevent the stagnation at the region underneath and around the rotor. Computational fluid dynamics (CFD) was adopted in this study to assess the performance and optimize the design to avoid recirculation and high shear stress which is the main cause of stagnation and blood damage. Transient simulation was used for this study due to the asymmetric design of the washout hole and the complication of the bottom support of the impeller that have a risk of thrombosis, also, it was used to predict the variation of hydraulic performance caused by the rotation of the impeller and pulsed flow at the pump inlet. The simulation results show no excessive stress and no recirculation observed within the computational domain; in addition, the research result also provided information for further optimization and development to the pump.     

红枣气体射流冲击干燥收缩特性研究

Chinese jujube originated in China and has a long historical standing. China is the only country which can produce a great amount of Chinese jujube in the world. Modern research showed that the nutrition of Chinese jujube is abundant. Chinese jujube has great medicinal and food value, with high economic value and good prospects for development. Shrinkage characteristics of dates generally refer to volume shrinkage characteristics of whole dates. Large fruit and plump grain appearance of dates is the first choice of consumers to buy elements. The volume of dried jujube points to the consumer’s heart, and is an important indicator of consumers whether to buy. Jujube processing enterprises grade the date in accordance with its size, different grades dates have different value and price. Therefore, drying is the most important steps during the dates processing as it affects directly the quality of the product, and the shrinkage characteristics is the most important quality characteristic of Chinese jujube after drying. However, the traditional natural desiccation and desiccation in the drying room of the red dates has many problems. The conventional drying method for Chinese jujube has some disadvantages of severe shrinkage, long drying time and large energy consumption etc. Therefore, in order to improve the quality of dried Chinese jujube and reduce the shrinkage, it is imperative to replace the traditional drying method with the modern technologies. Air impingement drying technology was applied to dry Chinese jujube. The drying characteristics of shrinkage, moisture effective diffusivity considering shrinkage characteristics and the activation energy of Chinese jujube shrinkage were investigated under different air temperatures (55, 60, 65 and 70℃) and air velocities (6, 9, 12 and 15m/s). The dynamic changes of the regular pattern for the shrinkage characteristic of Chinese jujube in the air impingement drying process were studied, the results showed that the volume relative shrinkage ratio of Chinese jujube appeared to increase and then decrease with the increase of air temperature and air velocity. Considering shrinkage characteristics, the moisture effective diffusivity of Chinese jujube in the air impingement drying process through the Fick’s second law was obtained. The diffusivity appeared to increase and then decrease with the decrease in moisture content in dry basis of Chinese jujube. The Arrhenius equation calculated the shrinkage activation energy of the Chinese jujube was 1281kJ/mol. This research provided technical basis for shrinkage characteristics of Chinese jujube using air impingement drying technology.     

Calculation of Irrigation Infiltration Recharge Coefficient and Analysis of Influencing Factors in the Lower Reaches of Aksu River北大核心CSCD

【Objective】In order to obtain the irrigation infiltration recharge coefficient in the lower reaches of Aksu river and improve the numerical simulation accuracy of groundwater in the study area,the influencing factors of the irrigation infiltration recharge coefficient in this area were analyzed. 【Method】In this paper,field sampling and indoor irrigation experiments were carried out by selecting representative points under different irrigation schemes,vadose zone thickness and soil structure in the lower Aksu area,and numerical simulation of vadose zone flow was carried out in combination with Hydrus-1d. Hydrus-1d model was used to calculate irrigation inflow under this soil structure by changing irrigation schemes and vadose zone thickness. Change of seepage recharge coefficient. On the basis of the calculation results of the model,the relationship between irrigation schedule,aeration zone thickness and irrigation infiltration recharge coefficient is analyzed firstly,and then the main factors affecting irrigation infiltration recharge coefficient in soil structure are analyzed with the method of model calculation and mathematical statistics. 【Result】The results showed that the irrigation infiltration recharge coefficient ranged from 0.320 to 0.474 under drip irrigation and from 0.408 to 0.561 under border irrigation. The irrigation infiltration recharge coefficient varied under different irrigation schemes,while the irrigation infiltration recharge coefficient decreased with the increase of aeration zone thickness. The main factors affecting irrigation infiltration recharge are soil permeability coefficient,soil bulk density and initial soil water content. 【Conclusion】According to indoor experiment combined with numerical model to calculate the irrigation infiltration coefficient under different irrigation system range, it is concluded that the influence factors of irrigation infiltration coefficient of irrigation system, the thickness of the vadose zone and reflects soil permeability coefficient of soil structure, soil quality and soil initial moisture content, volume for the downstream area irrigation infiltration coefficient selection in arid areas and provides the theory basis for further research. © 2019 Journal of Irrigation and Drainage. All rights reserved.     

Numerical study of hydrofoil surface j etflow on cavitation suppression

Cavitation caused vibration and noise of hydraulic machinery. To some extent,cavitation made fatigue damage in advance. Many scholars found that the re-entrant jets were the reasons of the shedding of cavities. To suppress cavitation,based on the idea of blocking the re-entrant jets,a special surface flow structure of 2D hydrofoil was proposed. The through-hole was made in the proper position of the hydrofoil. The incoming flow can outflow from this jet-hole automatically depending on the pressure difference between pressure side and suction side. Re-entrant jet growth can be weakened by optimizing the jet-hole geometry. Based on the standard k-ε turbulence model and Schnerr Sauer cavitation model,under different cavitation numbers( σ) and jet-angles( β) for NACA0066( 2D) hydrofoil with 8° angles of attack,cavitation field numerical analysis was carried out. The results show that 2D hydrofoil cavitation flow had a strong unsteadiness. Making a jet-hole at the junction between the re-entrant jet and cavity can effectively minimize cloud cavitation. For a certain cavitation condition,optimal jet-angles( β) can be obtained to control cavitation growth. For the same β,the effects of cavitation suppression were changed with different cavitation numbers( σ). Consequently,suitable jet-angle and jet-position could extend the stable operating range of the hydrofoil.