Through two groups of orthogonal tests(electrochemical corrosion current test and weight loss test),the order of water-quality factors which affect the corrosion behavior of A3 steel in eutrophic lakes is:pH > organic content(CODcr)>total phosphorus content > total nitrogen content.

Adopting the principal component analysis(PCA) method,we have established the synthetic model to assess those geological factors affecting surface subsidence and deformation.

The geological factors that cause unsuccessful drilling in different oil-bearing formations,different structural belts and different trap types are classified.

In order to predict gas correctly,the relation of gas content and geological factors in Qinsui Coal Field is studied,the gas preserving rule is analysed.

Strata quality factor (Q) and attenuation factor ( β ) especially these of near surface, are studied.

Simulation results show that better performance with smaller quality factor(Q) and boarder source moving range,and all these conclusions are obtained from viewpoints of the field uniformity and the probability density function(PDF).

Owing to the demand of oil and gas exploration and engineering prospecting,the research on acoustic attenuation of rocks is very active and quality factor Q is an important research field.