In the traditional analysis method of noise signals, it is very difficult to relate the overall noise from compressors to the angular position. The experimental method of separating the overall noise of different angular ranges is carried out at the real conditions. The starting position of the rotary piston is labelled with vane displacement and the test signals are synchronously sampled. Experimental results are analysed through fast Fourier transform method based on different angular ranges, which displays the following useful conclusions. The experiment technology could effectively identify the angular ranges for the frequency bands with prominent noise level; for the experimental rolling-piston compressor, the vibration, and sound pressure level of the discharge process (210-360 angular degrees) are the largest above the frequency 500 Hz. The discharge process is divided into three parts, where the final part contributes a little to the overall noise level when compared with the other two stages. Pressure pulsation is an important source of vibration and noise and its suppression of peak frequencies is the key of low-noise design of the compressor.
With the development of economic globalization, more and more internationally renowned chain retail enterprises are flooding into the Chinese retail market, which leads to the fierce competition of chain retail products. In order to gain market space in the fierce competition, Chinese chain retail enterprises usually adopt the form of cross-regional expansion. However, the cross-regional expansion of chain retail enterprises involves scattered entities and long chains, which brings supply chain risks to enterprises. For the sake of systematically identify the internal risks in the supply chain caused by the cross-regional expansion of chain retail enterprises, the improved SCOR model is adopted to identify the risks.
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