Improvement of gas-dynamic efficiency of GTE gas turbine stages at the design stage

Methods to control flow have been considered in order to reduce end losses in blade rows of GTE gas turbines by means of measures taken at the design stage.     

基于改进人工势场法的服务机器人路径规划

人工势场法是服务机器人路径规划算法中一种简单有效的方法.针对传统人工势场法存在的目标不可达问题,通过在原来的斥力函数中加入一个调节因子的方法解决,同时采用遍历搜索法解决局部极小值问题,并引入安全距离以及改进调节因子以提高机器人路径规划过程中的安全性能.最后,利用Matlab软件将改进后的人工势场法应用于服务机器人路径规划并进行了仿真实验.仿真结果表明,基于改进人工势场法的服务机器人路径规划有效地解决了机器人不能到达目标点的问题.     

Time-dependent cosmic ray modulation

Time-dependent cosmic ray modulation is calculated over multiple solar cycles using our well established two-dimensional time-dependent modulation model. Results are compared to Voyager 1, Ulysses and IMP cosmic ray observations to establish compatibility. A time-dependence in the diffusion and drift coefficients, implicitly contained in recent expressions derived by , ,  and , is incorporated into the cosmic ray modulation model. This results in calculations which are compatible with spacecraft observations on a global scale over consecutive solar cycles. This approach compares well to the successful compound approach of Ferreira and Potgieter (2004). For both these approaches the magnetic field magnitude, variance of the field and current sheet tilt angle values observed at Earth are transported time-dependently into the outer heliosphere. However, when results are compared to observations for extreme solar maximum, the computed step-like modulation is not as pronounced as observed. This indicates that some additional merging of these structures into more pronounced modulation barriers along the way is needed.     

Modeling of ionospheric scintillation at low-latitude

The presence and movement of plasma density fluctuations in the F-region of the ionosphere are studied by monitoring phase and amplitude of radio waves propagating through the region. In this paper, we have used weak scattering theory and assumed the plasma density fluctuations to behave like phase changing diffraction screen. Appropriate relations for scintillation index S₄, and phase variance δ? are derived and computed for different parameters of the plasma density irregularities of the ionosphere. SROSS-C2 satellite in situ measurements of plasma density fluctuations, which provide direct information about the structure and morphology of irregularities that are responsible for scintillation of radio waves, were used first time to develop a scintillation model for low latitude. It is observed that the scintillation index S₄ and phase variance δ? depends on the strength of the plasma turbulence. Finally, the results obtained from modeling are compared and discussed with the available recent results.