The reliability of the emergency flotation system of helicopters is analysed by using fault tree analysis and the Monte Carlo method. We constructed a fault tree with the failure of system as the top event and obtained the minimal cut set, the ranking of the structural importance of the bottom events and the probability of the occurrence of the top event. Based on the system fault tree, a Monte Carlo simulation model of the emergency flotation system is established by using Matlab/Simulink. The results show that the Monte Carlo method is feasible and effective for the reliability analysis of the emergency flotation systems of helicopters. Furthermore, the comparison between the criticality importance and mode importance of each subsystem suggests that the control component is the weakest part of the emergency flotation systems, thereby providing a basis for system reliability design and fault diagnosis.

Ag2S thin films were fabricated on the ITO-coated glass substrates by cathodically electro-deposition from the mixture solution including 0.01mol·L-1 AgNO3 and 0.05 mol·L-1 Na2S2O3 with pH=2.5 at room temperature. The microstructure and surface morphology of the films were investigated with the deposition potential (E) varied from -0.23V to -0.28V. The X-ray diffractograms show that the deposited films are monoclinic Ag2S with the relative deviation of cell parameters within 1.5%. The estimated cell parameters of the Ag2S films deposited at E = -0.25V are closest to those of the standard sample. The SEM pictures show that films are uniform with better compactness at more negative deposition potential, but there are some aggregation when the potential up to -0.28V. According to the AFM images, the root mean square (RMS) roughness and grain size decrease with the decreasing of potential absolute value, but they will increase when the deposition potential is too small. The best potential is -0.25V for depositing Ag2S thin films.

It is always the difficulties for micro hole machining in the machine manufacturing industry, even more in the defense industry. The vibration drilling new craft, with the incomparable advantages in micro hole drilling, is different from the common one. The precision NC micro hole vibration drilling machine is developed, and the micro hole drilling experiments are conducted. The vibration drilling can not only improve the drill life more than ten times compared with the normal one, but also improve the centering ability and position precision.

It is difficult to remove for burr, especially for micro-hole burr, so the vibration grinding process is put forward and adopted to remove burrs. The mechanism of vibration grinding deburring is analyzed, and the experiments of micro-hole deburring are done with the technology of vibration grinding. From the results of the experiments, the conclusion can be draw that this technology can remove the burrs effectively. The vibration grinding process has the features of simple process system, low cost, easy operating. The Vibration grinding process technology method can also be used to remove burrs of other machining process. It has more application value in practice.

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