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 sy...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.展开更多
In the present study, we aimed to investigate the effects of key extraction parameters including extraction time（10–20 min）, extraction temperature（30–60 °C）, ultrasonic power（60–90 W） and solvent-to-so...In the present study, we aimed to investigate the effects of key extraction parameters including extraction time（10–20 min）, extraction temperature（30–60 °C）, ultrasonic power（60–90 W） and solvent-to-solid（S/S） ratio（10–30 m L/g） on yield of celastrol from Celastrus monospermus Roxb. To optimize the conditions, we investigated the effects of parameters on the ultrasound assisted extraction（UAE） with the Box-Behnken Design（BBD）, one widely used form of Response Surface Methodology（RSM）. In all tested solvents, ethanol was the most effective for celastrol extraction, followed by methanol, ethanol, ethyl acetate, n-butanol and water. A second order polynomial model was fitted well to the extraction experimental data with R2 of 0.9928. Extraction yield of 3.116 mg/g was obtained for celastrol under the optimized extraction conditions of extraction time（20 min）, extraction temperature（46 °C）, ultrasonic power（60 W） and S/S ratio（30 m L/g）. Experimental validation was performed, and the experimental values agreed well with the predicted values. The results indicated that the UAE was good extraction material for celastrol from C. monospermus Roxb.展开更多
文摘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.
文摘In the present study, we aimed to investigate the effects of key extraction parameters including extraction time（10–20 min）, extraction temperature（30–60 °C）, ultrasonic power（60–90 W） and solvent-to-solid（S/S） ratio（10–30 m L/g） on yield of celastrol from Celastrus monospermus Roxb. To optimize the conditions, we investigated the effects of parameters on the ultrasound assisted extraction（UAE） with the Box-Behnken Design（BBD）, one widely used form of Response Surface Methodology（RSM）. In all tested solvents, ethanol was the most effective for celastrol extraction, followed by methanol, ethanol, ethyl acetate, n-butanol and water. A second order polynomial model was fitted well to the extraction experimental data with R2 of 0.9928. Extraction yield of 3.116 mg/g was obtained for celastrol under the optimized extraction conditions of extraction time（20 min）, extraction temperature（46 °C）, ultrasonic power（60 W） and S/S ratio（30 m L/g）. Experimental validation was performed, and the experimental values agreed well with the predicted values. The results indicated that the UAE was good extraction material for celastrol from C. monospermus Roxb.
