Cavitation is a common cause of failure in centrifugal pumps. Because of interaction of several mechanical parts and fluid, the vibration signal of a centrifugal pump is complicated. In this paper, the vibrations of a transparent-casing centrifugal pump are studied. Three states are studied experimentally: no cavitation, limited cavitation and developed cavitation. Each case was also confirmed by visually inspecting the cavitation bubbles. The vibrations of the pump was acquired by using an accelerometer that was attached to the casing. Discrete wavelet transform (DWT) analysis and empirical mode decomposition (EMD) are used to extract classification features from the acquired signals. Using these features, an artificial neural network (ANN) successfully diagnosed the cavitation condition of the pump. Finally, EEMD is also implemented. The results showed the success of EMD and DWT in cavitation diagnosis. The output of EEMD does not show significant change comparing to EMD.
Achieving competitive advantage enables an organization to create a defensible position against its competitors. It also allows organizations to differentiate themselves from competitors. This study aims to investigate impact of knowledge management practices on supply chain quality management and competitive advantage in Alyaf Company, Iran. This research is functional in purpose and data gathering and data analysis is descriptive-correlation. The statistical population is consists of 25 company executives and experts in the supply chain of Alyaf Company; opinions of 68 of its members were used as a selective sample identified by simple random sampling method. Primary data was collected through questionnaire and structural equation modeling was used to assess relationships between variables. The results of structural equation modeling show a positive and significant causal relationship between knowledge management practices and supply chain quality management. Direct relationship between knowledge management and competitive advantage was not confirmed but the relationship between these two variables was confirmed indirectly.
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