Study and simulation on the characteristics of drill string channel for acoustic waves

Traditional wireless MWD telemetry systems such as mud pulse and electromagnetic telemetry are limited due to low carrier frequencies. The first acoustic telemetry system was studied as part of a drill stem testing system in 2000, but there are some problems limited it to using for information transmission in drilling. In the paper, we study and simulation on the drill string channel characteristics. Based on the transmission equation of longitudinal wave in periodic drill string channel, we get a geometrical model for drill string channel. Two aspects are studied. Firstly, the equation for dispersion is established analyze and simulate the influence of length and cross-section to dispersion. Secondly, we introduce finite-difference for analyzing of transient response. Simulate transient response of drill string channel by changing the geometrical-characters of drill string. The paper gets characteristics of channel dispersion and signal attenuation, and useful for the choosing of best passband for carrier frequency. It is valuable for the acoustic telemetry to use for drilling applications.

肛泰栓对老年混合痔出血及排便功能影响的疗效观察

为观察肛泰栓对老年混合痔患者出血及排便功能的影响,将75例老年混合痔患者随机分为观察组37例和对照组38例。对照组患者采用高锰酸钾溶液坐浴治疗,观察组患者采用肛内纳入肛泰栓治疗,比较2组患者止血时间,治疗前、治疗2周时2组患者肛肠动力学指标生活质量评分。结果显示,观察组患者止血时间短于对照组(P <0.05);治疗2周时,2组患者RRP、ARP均低于治疗前,且观察组低于对照组(P <0.05);治疗2周时,2组患者生活质量评分均高于治疗前,且观察组高于对照组(P <0.05)。结果表明,肛泰栓可缩短老年混合痔患者止血时间,改善排便功能,提高患者生活质量。