为有效防控食芽象甲Scythropus yasumatsui K8no et Morimoto在陕西榆林地区枣园的危害,在田间调查的基础上,使用Iwao回归分析法、Taylor幂法则和5种常用指标参数,探明了成虫在不同枣园样地中的分布格局、理论抽样数及成虫的序贯抽样方...为有效防控食芽象甲Scythropus yasumatsui K8no et Morimoto在陕西榆林地区枣园的危害,在田间调查的基础上,使用Iwao回归分析法、Taylor幂法则和5种常用指标参数,探明了成虫在不同枣园样地中的分布格局、理论抽样数及成虫的序贯抽样方法。食芽象甲成虫在枣树上的空间格局为聚集型,个体间相互吸引,其聚集性随密度的增大而增加。对成虫进行序贯抽样,当每株成虫达到30头,置信水平为1.96时,序贯抽样进行抽样的防治下限与上限方程分别为:d_0=30n-34.33n^(1/2)和d1=30n+34.33 n^(1/2),当调查10株枣树上的虫数超过409头时,需要进行防治。食芽象甲成虫空间分布型及抽样方法的确定,对于揭示该虫的种群空间结构动态,提高田间测报准确率及防治效果都具有十分重要的意义。展开更多
The flow between two coaxial conical cylinders is numerically studied for two different configurations, with the inner cone rotating and the outer one at rest. It is found that, in one configuration,at least at a smal...The flow between two coaxial conical cylinders is numerically studied for two different configurations, with the inner cone rotating and the outer one at rest. It is found that, in one configuration,at least at a small Reynolds number（Re）, the pressure is a decreasing function of z while in the other configuration, it is an increasing function of z. In the first configuration, the pressure curves for different Re have intersections, while in the second configuration they do not. The gap between two conical cylinders is filled with six pairs of Taylor vortices at about the same Reynolds number and in each pair of vortices in the first configuration, the upper vortex is larger than the bottom one while in the second configuration, the bottom vortex is larger than the upper one.展开更多
基于交通测速雷达高精度、轻型化和小型化等要求,给出了以一种可用于交通测速的毫米波天线阵的设计。天线阵采用串并混合馈电方式,对天线单元以及馈电网络进行独立设计,对天线阵进行一体化设计和加工验证。天线阵采用串、并联方式进行馈...基于交通测速雷达高精度、轻型化和小型化等要求,给出了以一种可用于交通测速的毫米波天线阵的设计。天线阵采用串并混合馈电方式,对天线单元以及馈电网络进行独立设计,对天线阵进行一体化设计和加工验证。天线阵采用串、并联方式进行馈电,从而实现天线单元幅度的泰勒分布,使得天线阵在24~24.25 GHz的工作频段内,在E面和H面均获得小于-20 d B的低副瓣性能。整部天线阵具有轻型化、低副瓣和高增益等特点,满足作为交通测速雷达的需求。展开更多
An experimental study was carried out to understand the phenomena of the boiling flow of liquid nitrogen in an inclined tube with closed bottom by using a high speed motion analyzer. The experimental tube is 0.018 m I...An experimental study was carried out to understand the phenomena of the boiling flow of liquid nitrogen in an inclined tube with closed bottom by using a high speed motion analyzer. The experimental tube is 0.018 m ID and 1.0m in length. The range of the inclination angle is 45°-9° from the horizontal. The experiment focused on the effect of the inclination angle show that the mean liquid slug length and Taylor bubble length increase with the increasing xlD at various inclination angles. At the same x/D, the mean liquid slug length and Taylor bubble length increase first, and then decrease with decreasing inclination angles, with the maximum at 60°. In the vertical tube, standard deviation of the nitrogen Taylor bubble iength increase with the increasing xlD. For the inclined tube, standard deviation of the nitrogen Taylor bubble length increases first, and then decreases with the increasing x/D. Standard deviation of the liquid slug length increases with increasing x/D for all inclination angles.展开更多
Aiming at the limitation of traditional normal distribution structure is put forward. With strength-strain model, an improved algorithm for this method, the reliability coefficient of non-linear limit status function ...Aiming at the limitation of traditional normal distribution structure is put forward. With strength-strain model, an improved algorithm for this method, the reliability coefficient of non-linear limit status function is solved by developing Taylor progression, and the distribution parameters of random variables are estimated with experimental sample data. Therefore, the estimation of reliability confidence interval on certain confidence level can be solved when distribution parameters are unknown and limit status function is non-linear.展开更多
文摘The flow between two coaxial conical cylinders is numerically studied for two different configurations, with the inner cone rotating and the outer one at rest. It is found that, in one configuration,at least at a small Reynolds number（Re）, the pressure is a decreasing function of z while in the other configuration, it is an increasing function of z. In the first configuration, the pressure curves for different Re have intersections, while in the second configuration they do not. The gap between two conical cylinders is filled with six pairs of Taylor vortices at about the same Reynolds number and in each pair of vortices in the first configuration, the upper vortex is larger than the bottom one while in the second configuration, the bottom vortex is larger than the upper one.
文摘基于交通测速雷达高精度、轻型化和小型化等要求,给出了以一种可用于交通测速的毫米波天线阵的设计。天线阵采用串并混合馈电方式,对天线单元以及馈电网络进行独立设计,对天线阵进行一体化设计和加工验证。天线阵采用串、并联方式进行馈电,从而实现天线单元幅度的泰勒分布,使得天线阵在24~24.25 GHz的工作频段内,在E面和H面均获得小于-20 d B的低副瓣性能。整部天线阵具有轻型化、低副瓣和高增益等特点,满足作为交通测速雷达的需求。
基金Supported by the National Natural Science Foundation of China （50476015） and National High Technology Research and Development Program of China （2006AA09Z333）.
文摘An experimental study was carried out to understand the phenomena of the boiling flow of liquid nitrogen in an inclined tube with closed bottom by using a high speed motion analyzer. The experimental tube is 0.018 m ID and 1.0m in length. The range of the inclination angle is 45°-9° from the horizontal. The experiment focused on the effect of the inclination angle show that the mean liquid slug length and Taylor bubble length increase with the increasing xlD at various inclination angles. At the same x/D, the mean liquid slug length and Taylor bubble length increase first, and then decrease with decreasing inclination angles, with the maximum at 60°. In the vertical tube, standard deviation of the nitrogen Taylor bubble iength increase with the increasing xlD. For the inclined tube, standard deviation of the nitrogen Taylor bubble length increases first, and then decreases with the increasing x/D. Standard deviation of the liquid slug length increases with increasing x/D for all inclination angles.
文摘Aiming at the limitation of traditional normal distribution structure is put forward. With strength-strain model, an improved algorithm for this method, the reliability coefficient of non-linear limit status function is solved by developing Taylor progression, and the distribution parameters of random variables are estimated with experimental sample data. Therefore, the estimation of reliability confidence interval on certain confidence level can be solved when distribution parameters are unknown and limit status function is non-linear.
