Abstract. The development and application of Decision Support System (DSS) promote the development of related industries, special equipment accident analysis also need the support of decision support system due to variety kinds of special equipment and changeable accident cause. It was expounded definition, development situation, classification, arithmetic and existing problems of DSS according to the characteristics of special equipment accidents analysis. Research shows that there are both difference and relation among five kinds of DSS. It introduces Bayesian network and the difference of Bayesian network modeling method. The reasoning modeling method based on knowledge could use both the empirical knowledge of experts and the computer aided technology, but it is limited by the quantity and quality of expert experience knowledge similar to artificial modeling method based on expert. The application of big data, cloud computing and other related technologies in DSS would stimulate the development of DSS. It provided the technology accumulation for exploitation and application of special equipment accident analysis DSS.
9Ni steel has good toughness and high strength. This paper focuses on the influence of vertical hole defects on the ultrasonic propagation characteristics, which are studied from two aspects of the propagation characteristics of the base metal and the ultrasonic waves of the weld, respectively. The acoustic reflection characteristics of the reflector are compared with the acoustic reflection characteristics of the two different welding processes, (manual welding and automatic welding). It is shown that the gain compensation of the weld is larger than the gain of the same diameter and the same position of the vertical hole in the base metal. The gain compensation of the automatic welding is larger than that of the manual welding. The ultrasonic attenuation in the automatic welding is larger than that of the manual welding. The results of the study contribute to improving the application of ultrasonic testing in 9Ni weld joints.
20MnMoNb alloy steel is a structural steel for forgings with good mechanical properties, which is typically used in the manufacture of pressure vessel tube sheets. The mechanical properties of 20MnMoNb at different temperatures were systematically studied. It is shown that the 20MnMoNb material has the good high temperature resistance. With the increase of temperature, the yield strength and tensile strength of the material have little difference. The tensile strength is nearly 800MPa at high temperature, and the yield strength is about 643MPa, which could meet the complex working environment of the high pressure heaters. It is helpful to improve the accuracy of analytical design results and provide a data base for the revision of subsequent material standards.
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