In order to solve the problem of underdetermined blind source separation (BSS) in the diagnosis of compound fault of roller bearings, an underdetermined BSS algorithm based on null-space pursuit (NSP) was proposed. In this algorithm, the signal model of faulty roller bearing is firstly used to construct an appropriate differential operator in null space. With the constructed differential operator, the mixed signals collected by the vibration sensor are decomposed into a series of stacks of narrow band signal containing the characteristics of faulty bearing. Finally, the underdetermined problem is transformed to an overdetermined problem by combining the narrow band signals and the original mixed signals into a new group of observed signals. In this way, the separation of the mixed signals can be realized. Experiments and engineering data analyses show that the problem of underdetermined BSS can be solved effectively by this approach, and then the compound fault of the roller bearing can be separated.
an ozone-biological aerated filter process was operated for more than one year to evaluate its feasibility in polishing the secondary effluent of domestic wastewater treatment. The average effluent COD, UV 254 , color, turbidity, NH 3 -N were 33.8 mg/L, 0.148 cm -1 , 12.6, 1.3 NTU and 6.4 mg/L with the corresponding removal rates 51.9%, 26.6%, 77.2%, 76.4%, 78.0% respectively. Main operational parameters were: ozone dosage 16 mg/L, ozone reaction time 15 min, hydraulic retention time of the biological aerated filter 1 h, ratio of air to water 3:1.The filtration bed of the biological aerated filter was filled with 1 m high 1~1.2 mm quartz sand. All results showed excellent performance of the ozone-biological aerated filter process. Experiences proved that the operation parameters such as dosage of ozone should be changed with the influent quality to acquire the best quality of the effluent.
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