Gas valves are very important parts in compressors. If a valve fault in a compressor takes place, the expulsion of the compressor will decrease. In some critical cases, abnormal gas transmission will lead to a serious accident. This article proposes a method of fixed time basis in multi-resolution analysis and wavelet transform. This method can thoroughly resolve the problems occurred in present valve fault diagnosis caused by the fact that the wavelet transform does not have time shift invariance. By the analysis of experimental data, it shows that the valve fault can be preferably and accurately detected by using the method.

In this paper the molding mechanisms of mibration compaction for concrete bricks is explained. A lot of concrete bricks with different ash content were by a vibration compaction machines produced. The characteristics of the concrete bricks are investigated. The experiments showed that the starting hardness of the concrete bricks at the separation from molding tools is sufficient for brick stacking.