基于连续覆盖特性分析的星座设计

研究了需要对地面目标进行连续覆盖的星座的设计问题．首先推导了对覆盖性能有重要影响的星间覆盖间隔时间和轨道面覆盖间隔时间的计算公式，通过算例针对不同配置的星座进行了计算，使用工程仿真软件STK验证了分析结果．通过理论分析、算例计算以及工程仿真为该类型星座设计提供了理论指导。     

Study of the variability of blazars gamma-ray emission

The γ-ray emission of blazar jets shows a pronounced variability and this feature provides limits to the size and to the speed of the emitting region. We study the γ-ray variability of bright blazars using data from the first 18 months of activity of the Large Area Telescope on the Fermi Gamma-Ray Space Telescope. From the daily light-curves of the blazars characterized by a remarkable activity, we firstly determine the minimum variability time-scale, giving an upper limit for the size of the emitting region of the sources, assumed to be spheroidal blobs in relativistic motion. These regions must be smaller than ∼10⁻³ parsec. Another interesting time-scale is the duration of the outbursts. We conclude that they cannot correspond to radiation produced by a single blob moving relativistically along the jet, but they are either the signature of emission from a standing shock extracting energy from a modulated jet, or the superposition of a number of flares occurring on a shorter time-scale. We also derive lower limits on the bulk Lorentz factor needed to make the emitting region transparent for gamma-rays interacting through photon–photon collisions.     

数字化技术在叶轮研制中的应用

本文通过分析归纳建立了一种叶轮数字化建模方法，并利用该方法成功实现了某型叶轮三维模型创建，同时也根据该数字化模型实现了模具数字化设计及其数控加工。     

The beaming of external Compton emission

We consider a relativistically moving blob consisting of an isotropic electron distribution that Compton-scatters photons from an external isotropic radiation field. We compute the resulting beaming pattern, i.e. the distribution of the scattered photons, in the blob frame as well as in the observer’s frame by using the full Klein–Nishina cross section and the exact incident photon distribution. In the Thomson regime the comparison of our approach with Dermer (1995) results in concurrent characteristics but different absolute number of the scattered photons by a factor of f_corr = 3.09. Additionally, our calculation yields a slightly lower boost factor which varies the more from the corresponding value in Dermer (1995) the higher the spectral index p of the electron distribution gets.     

基于Visual Basic的互感器负荷箱测量仪校准系统的实现

为解决互感器负荷箱测量仪同相分量和正交分量的校准问题,在分析互感器负荷箱测量仪工作原理的基础上,设计了基于电子/电工组合式的互感器负荷箱测量仪校准装置,并简要说明装置电工部分、电子部分以及上位机软件的实现。经省级计量研究院验证结果表明,该装置校准结果符合0.2级要求,可作为标准装置解决1级互感器负荷箱测量仪量值溯源问题。     

An equilibrium multi-objective optimum design for non-circular clearance hole of disk with discrete variables

An Equilibrium Multi-objective Optimization Model(EMOM) with self-regulated weighting factors has been proposed for the optimum design of non-circular clearance hole on the front flange of turbine disk. In the ‘‘equilibrium design", both the stress decrease around the hole and the least hole's profile variation are considered, which balances two ambivalent design goals. Specific discrete variables are applied to realize the standardization design in the optimization process, in which a Surrogate Genetic Coding Algorithm(SGCA) is introduced, and a special check module is used to get rid of repeated fitness evaluation of the samples. The method offers an equilibrium design for the non-circular clearance hole of the turbine disk with great accuracy and efficiency.     

任务型教学法的任务设计

任务型教学法是新兴的一种强调“在做中学”(learning by doing)的语言教学方法，是我国外语课程教学改革的一个走向，吸收了以往多种教学法的优点而形成。任务是任务型教学法中一个重要概念。要使任务型教学法更好地发挥作用，任务的设计就显得尤为重要。在任务设计中，要注意任务与人本主义、任务与文化性、任务与教师角色之...     

基于等效板的含离散源损伤机翼结构分析

研究离散源损伤对机翼结构的影响,可以大幅度提高飞机在不良损伤事故下的生存能力.由于机翼内部结构复杂,很难对含离散源损伤机翼结构进行精确分析,而且精确的建模和仿真在建模与计算过程中往往也非常耗时.因此,以含离散源损伤机翼为对象,采用有限元优化设计方法,确立了一种机翼结构等效板模型的建模方法.建立的等效板模型可对含离散源损伤机翼实现快速、准确的静力学和动力学分析.     

阵风载荷减缓系统故障分析

阵风引起的额外载荷会引起飞机结构疲劳,降低结构使用寿命。采用非定常气动力有理函数拟合方法建立时域状态空间下的动力学系统,设计了阵风载荷减缓系统。研究了阵风载荷减缓系统3种典型故障模式(副翼偏转饱和、舵机卡死、副翼偏转延时)的力学建模方法,并对机翼在阵风减缓系统故障模式下的阵风响应进行分析。仿真结果表明,3种故障模式均不利于阵风载荷减缓系统对阵风载荷的减缓,对于一些特定情况,故障模式下的阵风载荷减缓系统不仅不能减缓阵风载荷,还会带来由副翼偏转不当引起的额外负载。