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Measurement quality and analysis capability of infrasonic signals are both affected by background wind-noise. Physical filters, i.e., barriers and pipe arrays, are traditionally employed to reduce such noise. However, limited efficacy, site dependence, cost, requirement of space, non-portability, and frequent maintenance are some of their major drawbacks. This work proposes an adaptive filtering-based adaptive line enhancer (ALE) noise cancellation scheme as an alternative. Two infrasonic sensors (Chaparral Physics 50A), are adjacently deployed. One sensor is fitted with a conventional four-armed non-porous hose array (physical filter), while the ALE scheme is applied to the second sensor, sans physical filter. In high wind-noise conditions, the ALE scheme seems to behave as a lowpass filter (cutoff at 0.2 Hz), with a maximum attenuation of 26 dB at 8 Hz, while the physical filter provides significant attenuation only above 4 Hz with a maximum attenuation of 17 dB at 8 Hz. Generally, at other frequencies, the ALE scheme provides up to 20 dB superior noise attenuation as compared to the physical filter. The ALE also provides up to 6 dB gain in the signal-to-noise ratio as compared to the physical filter, due to non-attenuation of the infrasonic signal.

A pin on disk machine is designed and constructed to experimentally measure and investigate the friction coefficient and wear rate of two groups of compounds of (PET) -CNT, and PET -CNT and paraffin oil under variable applied loads. Polymeric Composites Reinforced by Nano Particles and Impregnated with Paraffin Oil have low friction coefficients and highly resistant to wear so it is widely used in aerospace, automobiles, packing materials and in bearing applications.The effect of both percentages of PET with CNT and PET, CNT and paraffin oil under variable loads on coefficient of friction and wear values are carefully recorded and studied.A historical review of the available published work has shown a need for this work. This research used test specimens were prepared by casting method. The Addition of carbon Nanotubes to the polyethylene terephthalate with specified contents of Group I showed decrease in friction coefficient and wear values with increasing CNT content and applied loads.The tested specimens of Group II were filled by 3, 5, 10 wt. % paraffin oil introduced with the composites of PET and CNT. Applied loads of 8, 13, 18, 23, 28, 33 N were used during the test. The coefficient of friction was calculated by dividing the frictional forces by the applied normal load. Specimens were weighed before and after the test and the difference between the two weights represented the wear loss.Results of conducted tests on the compound of PET and CNT and paraffin oil under the previous loads were plotted for friction coefficient as of CNT content showed decreasing trend of friction coefficient with increasing the content of paraffin oil. According to increase of the applied loads of wear rate decreased.