Using a crop-water-salinity production function and a soil-water-salinity dynamic model, optimal irrigation scheduling was developed to maximize net return per irrigated area. Plot and field experiments were used to o...Using a crop-water-salinity production function and a soil-water-salinity dynamic model, optimal irrigation scheduling was developed to maximize net return per irrigated area. Plot and field experiments were used to obtain the crop water sensitivity index, the salinity sensitivity index, and other parameters. Using data collected during 35 years to calculate the 10-day mean precipitation and evaporation, the variation in soil salinity concentrations and in the yields of winter wheat and cotton were simulated for 49 irrigation scheduling that were combined from 7 irrigation schemes over 3 irrigation dates and 7 salinity concentrations of saline irrigation water (fresh water and 6 levels of saline water). Comparison of predicted results with irrigation data obtained from a large area of the field showed that the model was valid and reliable. Based on the analysis of the investment cost of the irrigation that employed deep tube wells or shallow tube wells, a saline water irrigation schedule and a corresponding strategy for groundwater development and utilization were proposed. For wheat or cotton, if the salinity concentration was higher than 7.0 g L-1 in groundwater, irrigation was needed with only fresh water; if about 5.0 g L-1, irrigation was required twice with fresh water and once with saline water; and if not higher than 3.0 g L-1, irrigation could be solely with saline water.展开更多
With the background of offshore wind energy projects, this paper studies aerodynamic performance and geometric characteristics of large capacity wind turbine rotors （1 to 10 MW）, and the main characteristic paramete...With the background of offshore wind energy projects, this paper studies aerodynamic performance and geometric characteristics of large capacity wind turbine rotors （1 to 10 MW）, and the main characteristic parameters such as the rated wind speed, blade tip speed, and rotor solidity. We show that the essential criterion of a high- performance wind turbine is a highest possible annual usable energy pattern factor and a smallest possible dimension, capturing the maximum wind energy and producing the maximum annual power. The influence of the above-mentioned three parameters on the pattern factor and rotor geometry of wind turbine operated in China＇s offshore meteoro- logical environment is investigated. The variation patterns of aerodynamic and geometric parameters are obtained, analyzed, and compared with each other. The present method for aerodynamic analysis and its results can form a basis for evaluating aerodynamic performance of large-scale offshore wind turbine rotors.展开更多
目的分析早产儿脑白质损伤(WMD)早期相关高危因素。方法选取郑州大学第二附属医院2018-10—2019-05住院的210例早产儿,根据出生后2周内头颅磁共振结果有无异常分为WMD组及对照组。对比2组患儿在围生期的情况及检查结果,进行单因素分析,...目的分析早产儿脑白质损伤(WMD)早期相关高危因素。方法选取郑州大学第二附属医院2018-10—2019-05住院的210例早产儿,根据出生后2周内头颅磁共振结果有无异常分为WMD组及对照组。对比2组患儿在围生期的情况及检查结果,进行单因素分析,对单因素分析中的显著因素进行多因素Logistic回归分析。结果210例早产儿中,诊断出WMD共61例,其中轻度30例,中度28例,重度3例,发生率29.04%。单因素分析提示,胎膜早破、脐绕颈、早产、低出生体质量、新生儿窒息、呼吸窘迫、围生期感染、辅助通气2组间比较差异有统计学意义(P<0.05)。Logistic回归分析显示,5 min Apgar评分(OR=2.221,P=0.001)、第1周血管活性药物应用(OR=1.541,P=0.043)及感染(OR=3.612,P=0.02)是独立危险因素。结论多种因素均能影响早产儿WMD的发生,其中窒息史、血流动力学改变及围生期感染是主要的危险因素,临床应针对这些因素,对早产儿采取相应处理措施,以预防WMD的发生。展开更多
Hydrodynamic lubrications between two plane plates with an intersection angle θ have been investigated us- ing the boundary slippage theory, and relations are obtained between dimensionless pressures and coordinate x...Hydrodynamic lubrications between two plane plates with an intersection angle θ have been investigated us- ing the boundary slippage theory, and relations are obtained between dimensionless pressures and coordinate x, between bearing capacity, friction force, friction coefficient and di- mensionless slipping size factor. The results show that bear- ing capacity of two plane plates without boundary slippage significantly increases with increasing intersection angle θ when 0 〈 θ 〈 1°, whereas decreases with increasing in- tersection angle 0 when θ 〉 1°. The results also show that negative pressure occurs in fluid entrance region and bearing capacity decreases, and friction force and friction coefficient increase with the increase of dimensionless slipping size fac- tor.展开更多
Incorporation of the Barnegat Bay into the US National Estuary Program has triggered collection and collation of basic data sets appropriate to estuarine management. Gathering of water quality and quantity as well as ...Incorporation of the Barnegat Bay into the US National Estuary Program has triggered collection and collation of basic data sets appropriate to estuarine management. Gathering of water quality and quantity as well as basic geological data is adding to the knowledge of the complexity of the bay. An ongoing program of systematic sampling of bottom sediments in the large bay and intense sampling in the many micro-estuaries along the mainland margin is demonstrating the presence of localized mor-pho-sedimentological units related to the interaction of the fluvial, tidal, and wave processes active in the bay. Mean grain sizes and standard deviation measures assist in the development of signatures of bottom sediment types.展开更多
The extended finite element method is used to analyze a plate with two parallel edge cracks impacted by a cylindrical projectile. The influence of the impact speed, crack length, plate thickness and notch tip radius o...The extended finite element method is used to analyze a plate with two parallel edge cracks impacted by a cylindrical projectile. The influence of the impact speed, crack length, plate thickness and notch tip radius on the crack initiation and propagation is studied. Dynamics equations are solved by an implicit time integration scheme which is unconditionally stable. Very good agreement is achieved between numerical predictions and experimental results. The critical velocity of the crack initiation under different conditions is examined. The influence of the crack length is greater than that of the impact speed, plate thickness and notch tip radius.展开更多
基金Project supported by the National Natural Science Foundation of China (Nos. 50339030 and 90202001).
文摘Using a crop-water-salinity production function and a soil-water-salinity dynamic model, optimal irrigation scheduling was developed to maximize net return per irrigated area. Plot and field experiments were used to obtain the crop water sensitivity index, the salinity sensitivity index, and other parameters. Using data collected during 35 years to calculate the 10-day mean precipitation and evaporation, the variation in soil salinity concentrations and in the yields of winter wheat and cotton were simulated for 49 irrigation scheduling that were combined from 7 irrigation schemes over 3 irrigation dates and 7 salinity concentrations of saline irrigation water (fresh water and 6 levels of saline water). Comparison of predicted results with irrigation data obtained from a large area of the field showed that the model was valid and reliable. Based on the analysis of the investment cost of the irrigation that employed deep tube wells or shallow tube wells, a saline water irrigation schedule and a corresponding strategy for groundwater development and utilization were proposed. For wheat or cotton, if the salinity concentration was higher than 7.0 g L-1 in groundwater, irrigation was needed with only fresh water; if about 5.0 g L-1, irrigation was required twice with fresh water and once with saline water; and if not higher than 3.0 g L-1, irrigation could be solely with saline water.
基金supported by the National Basic Research Program of China (973 Program) (No. 2007CB714605)
文摘With the background of offshore wind energy projects, this paper studies aerodynamic performance and geometric characteristics of large capacity wind turbine rotors （1 to 10 MW）, and the main characteristic parameters such as the rated wind speed, blade tip speed, and rotor solidity. We show that the essential criterion of a high- performance wind turbine is a highest possible annual usable energy pattern factor and a smallest possible dimension, capturing the maximum wind energy and producing the maximum annual power. The influence of the above-mentioned three parameters on the pattern factor and rotor geometry of wind turbine operated in China＇s offshore meteoro- logical environment is investigated. The variation patterns of aerodynamic and geometric parameters are obtained, analyzed, and compared with each other. The present method for aerodynamic analysis and its results can form a basis for evaluating aerodynamic performance of large-scale offshore wind turbine rotors.
文摘目的分析早产儿脑白质损伤(WMD)早期相关高危因素。方法选取郑州大学第二附属医院2018-10—2019-05住院的210例早产儿,根据出生后2周内头颅磁共振结果有无异常分为WMD组及对照组。对比2组患儿在围生期的情况及检查结果,进行单因素分析,对单因素分析中的显著因素进行多因素Logistic回归分析。结果210例早产儿中,诊断出WMD共61例,其中轻度30例,中度28例,重度3例,发生率29.04%。单因素分析提示,胎膜早破、脐绕颈、早产、低出生体质量、新生儿窒息、呼吸窘迫、围生期感染、辅助通气2组间比较差异有统计学意义(P<0.05)。Logistic回归分析显示,5 min Apgar评分(OR=2.221,P=0.001)、第1周血管活性药物应用(OR=1.541,P=0.043)及感染(OR=3.612,P=0.02)是独立危险因素。结论多种因素均能影响早产儿WMD的发生,其中窒息史、血流动力学改变及围生期感染是主要的危险因素,临床应针对这些因素,对早产儿采取相应处理措施,以预防WMD的发生。
文摘Hydrodynamic lubrications between two plane plates with an intersection angle θ have been investigated us- ing the boundary slippage theory, and relations are obtained between dimensionless pressures and coordinate x, between bearing capacity, friction force, friction coefficient and di- mensionless slipping size factor. The results show that bear- ing capacity of two plane plates without boundary slippage significantly increases with increasing intersection angle θ when 0 〈 θ 〈 1°, whereas decreases with increasing in- tersection angle 0 when θ 〉 1°. The results also show that negative pressure occurs in fluid entrance region and bearing capacity decreases, and friction force and friction coefficient increase with the increase of dimensionless slipping size fac- tor.
基金Support for this project was provided by The Trust for Public Lands, the New Jersey Sea Grant Program, and the Institute of Marine and Coastal Sciences, Rutgers University. Field and laboratory assistance was ably provided by Natalie Pitchford, Adam Levy
文摘Incorporation of the Barnegat Bay into the US National Estuary Program has triggered collection and collation of basic data sets appropriate to estuarine management. Gathering of water quality and quantity as well as basic geological data is adding to the knowledge of the complexity of the bay. An ongoing program of systematic sampling of bottom sediments in the large bay and intense sampling in the many micro-estuaries along the mainland margin is demonstrating the presence of localized mor-pho-sedimentological units related to the interaction of the fluvial, tidal, and wave processes active in the bay. Mean grain sizes and standard deviation measures assist in the development of signatures of bottom sediment types.
基金supported by the National Natural Science Foundation of China(Nos.11272096 and 11472086)the Research Fund for the Doctoral Program of Higher Education of China(No.20112304110015)
文摘The extended finite element method is used to analyze a plate with two parallel edge cracks impacted by a cylindrical projectile. The influence of the impact speed, crack length, plate thickness and notch tip radius on the crack initiation and propagation is studied. Dynamics equations are solved by an implicit time integration scheme which is unconditionally stable. Very good agreement is achieved between numerical predictions and experimental results. The critical velocity of the crack initiation under different conditions is examined. The influence of the crack length is greater than that of the impact speed, plate thickness and notch tip radius.
