Classification of mine blasts and microseismic events using starting-up features in seismograms

To find discriminating features in seismograms for the classification of mine seismic events,signal databases of blasts and microseismic events were established based on manual identification.Criteria including the repetition of waveforms,tail decreasing,dominant frequency and occurrence time of day were considered in the establishment of the databases.Signals from databases of different types were drawn into a unified coordinate system.It is noticed that the starting-up angles of the two types tend to be concentrated into two different intervals.However,it is difficult to calculate the starting-up angle directly due to the inaccuracy of the P-wave arrival＇s picking.The slope value of the starting-up trend line,which was obtained by linear regression,was proposed to substitute the angle.Two slope values associated with the coordinates of the first peak and the maximum peak were extracted as the characteristic parameters.A statistical model with correct discrimination rate of greater than 97.1% was established by applying the Fisher discriminant analysis.

Influences of characteristic parameters on starting-up process of an arcjet thruster

Arcjet thruster has been a widely used electrical propulsion technology on GEO satellites since 1993.In its long history of technical development and commercial application,lifetime verification of an arcjet thruster is always one of the most important and expensive tasks.Considering that the main life limitation of an arcjet thruster is electrode ablation and a significant share of the total ablation happens in its starting-up process,the starting-up process is studied with arc voltage signals.Through interpretation of arc voltage signals,the transfer process of the arc root on the anode surface is identified,and?T(the duration of the arc root transfer process)is suggested to be a characteristic parameter for fast evaluation of lifetime assessment and design optimization for an arcjet thruster.With this criterion,the influences of typical parameters on the starting-up process are established through comparison with a benchmark parameter.According to experimental results,an increase of the gas flow will obviously reduce?T,while a smaller swirl aperture and a longer throat channel do not have a remarkable correlation with?T.Moreover,with a sample of a smaller throat diameter to increase the flow velocity,a reduction of?T is achieved.Meanwhile,the modifications also affect the stability of arcjet thruster operation,which is also discussed.

芜湖新兴1#1280m^3高炉中修开炉总结

芜湖新兴铸管1280m^3高炉中修28天,通过精确计算开炉料,开炉过程中外围精心组织,炉内及时调整开炉操作参数,开炉2天内恢复全风操作,第5天日产达3800T以上,各项经济技术指标得到优化,实现了快速开炉达产的目标。