Railway Axle Early Fatigue Crack Detection through Condition Monitoring Techniques.

The detection of cracks in rotating machinery is an unresolved issue today. In this work, a methodology for condition monitoring of railway axles is presented, based on crack detection by means of the automatic selection of patterns from the vibration signal measurement. The time waveforms were processed using the Wavelet Packet Transform, and appropriate alarm values for diagnosis were calculated automatically using non-supervised learning techniques based on Change Point Analysis algorithms. The validation was performed using vibration signals obtained during fatigue tests of two identical railway axle specimens, one of which cracked during the test while the other did not. During the test in which the axle cracked, the results show trend changes in the energy of the vibration signal associated with theoretical defect frequencies, which were particularly evident in the direction of vibration that was parallel to the track. These results are contrasted with those obtained during the test in which the fatigue limit was not exceeded, and the test therefore ended with the axle intact, verifying that the effects that were related to the crack did not appear in this case. With the results obtained, an adjusted alarm value for a condition monitoring process was established.

Establishment and Application of Prevalence Baseline for Hospital Infection / 中华医院感染学杂志

OBJECTIVE To establish the mechanism for monitoring,standardizing and alarming of relative risk factors to reflect the tendency of hospital infection.METHODS Data of hospital infection during six years were surveyed and analyzed completely.The prevalence baseline of hospital infection was chosen as the value to assess the control rate of hospital infection.The alarm value was set on the baseline.RESULTS The hospital infection revalence baseline and alarm value were used to assess the quality of infection control in whole hospital and each department objectively and accurately.These values could be also used to assess the effect of control of hospital infection among departments.They also could be used to survey the tendency of hospital infection and determine prevalence and outbreak of hospital infection.CONCLUSIONS Prevalence baseline and alarm value for hospital infection are valuable for preventing hospital infection and its outbreak.