Directional drilling has been established in the coal industry as a viable means of gas drainage, exploration and water management. But the environment in and around coal seams is not always conducive to stable condit...Directional drilling has been established in the coal industry as a viable means of gas drainage, exploration and water management. But the environment in and around coal seams is not always conducive to stable conditions while drilling and borehole stability after the drilling has been completed. This paper identifies the conditions which cause unstable drilling conditions and the various means which are used to attempt to manage or bypass those conditions. Ultimately, equipment does become bogged in these adverse environments and requires recovery by over-coring.展开更多
选取ING Direct Canada和ING Direct USA两家直销银行1997~2007年在北美的发展历程,分析ING Direct秉持的营销理念和价值主张,重点分析ING Direct金融服务营销的价值创造逻辑、要点以及优势在其金融服务活动中的体现,探讨了案例企业服...选取ING Direct Canada和ING Direct USA两家直销银行1997~2007年在北美的发展历程,分析ING Direct秉持的营销理念和价值主张,重点分析ING Direct金融服务营销的价值创造逻辑、要点以及优势在其金融服务活动中的体现,探讨了案例企业服务营销对社会理财观念和行为的影响,为我国金融业服务营销理念和经营模式的变革提供思路和参考。展开更多
电气设备局部放电超声阵列定位是将超声阵列传感器与阵列信号处理技术应用于局部放电超声定位的一种新方法。研究表明,传统的测向算法对双局放源的定位精度不足,分辨力较低;满阵传感器结构复杂且成本昂贵,不适合工程应用。据此,提出一...电气设备局部放电超声阵列定位是将超声阵列传感器与阵列信号处理技术应用于局部放电超声定位的一种新方法。研究表明,传统的测向算法对双局放源的定位精度不足,分辨力较低;满阵传感器结构复杂且成本昂贵,不适合工程应用。据此,提出一种基于改进RD-MUSIC(Reduced Dimension-Multiple Signal Classification)的测向算法和稀疏方形阵列传感器的双局放源检测方法。以稀疏度为4阶的4×4方形平面阵列传感器为例,研究了基于改进RD-MUSIC算法的双局放源的波达方向估计算法的有效性。仿真结果显示改进RD-MUSIC算法得到的测向星谱图可直观获得DOA估计量,提高了计算速度和测向精度,实验验证了该方法的有效性。展开更多
文摘Directional drilling has been established in the coal industry as a viable means of gas drainage, exploration and water management. But the environment in and around coal seams is not always conducive to stable conditions while drilling and borehole stability after the drilling has been completed. This paper identifies the conditions which cause unstable drilling conditions and the various means which are used to attempt to manage or bypass those conditions. Ultimately, equipment does become bogged in these adverse environments and requires recovery by over-coring.
文摘选取ING Direct Canada和ING Direct USA两家直销银行1997~2007年在北美的发展历程,分析ING Direct秉持的营销理念和价值主张,重点分析ING Direct金融服务营销的价值创造逻辑、要点以及优势在其金融服务活动中的体现,探讨了案例企业服务营销对社会理财观念和行为的影响,为我国金融业服务营销理念和经营模式的变革提供思路和参考。
文摘电气设备局部放电超声阵列定位是将超声阵列传感器与阵列信号处理技术应用于局部放电超声定位的一种新方法。研究表明,传统的测向算法对双局放源的定位精度不足,分辨力较低;满阵传感器结构复杂且成本昂贵,不适合工程应用。据此,提出一种基于改进RD-MUSIC(Reduced Dimension-Multiple Signal Classification)的测向算法和稀疏方形阵列传感器的双局放源检测方法。以稀疏度为4阶的4×4方形平面阵列传感器为例,研究了基于改进RD-MUSIC算法的双局放源的波达方向估计算法的有效性。仿真结果显示改进RD-MUSIC算法得到的测向星谱图可直观获得DOA估计量,提高了计算速度和测向精度,实验验证了该方法的有效性。
