A case study: Monitoring heat exchanger based on vibration sensors and nondestructive testing technique
Flow-induced tube vibration could cause serious damage on large-scale circulating-water heat exchanger in factories, e.g., atomic reactors, nuclear power plants, petroleum and chemical industry. Therefore, efficient inspection technology is very important for heat exchanger's blockage and leakage. The existing detection technologies, like temperature test and pressure test, are very easily affected by extraneous factors, e.g., temperature and pressure, while the nondestructive testing technology based on vibration sensors is free from above limits. In this paper, we use vibration sensors to detect blockage and leakage of the circulating-water heat exchanger. According to the experimental results, it is found that when detecting heat exchanger's blockage and leakage with vibration sensors, environmental vibration from the working machines has influence upon the result, while pump vibration and vibration produced by liquid flowing through regulating-valve make little difference. Nevertheless, fault diagnosis of large-scale circulating-water heat exchanger, which uses nondestructive testing technology based on vibration sensors, needs to be further improved.
Vibration Sensor Based Intelligent Fault Diagnosis System for Large Machine Unit in Petrochemical Industries
Fault diagnosis is an area which is gaining increasing importance in rotating machinery. Along with the continuous advance of science and technology, the structures of rotating machinery become increasingly of larger scale and higher speed and more complicated, which result in higher probability of various failure in practice. In case one of the most critical components of machinery or equipment breaks down, it cannot only cause enormous economic loss, but also easily cause the loss of many people's lives. It is important to enable reliable, safe, and efficient operation of large-scale and critical rotating machinery, which requires us to achieve accurate and fast diagnosis of fault which has occurred. Aiming at dynamic real-time vibration monitoring and vibration signal analysis for large machine unit in petrochemical industry, which cannot realize real-time, online, and fast fault diagnosis, an intelligent fault diagnosis system using artificial immune algorithm and dimensionless parameters is developed in this paper, innovated with a focus on reliability, remote monitoring, and practicality and applied to the third catalytic flue gas turbine in a petrochemical enterprise, with good effects.
On the Graph Edit Distance Cost: Properties and Applications
We model the edit distance as a function in a labeling space. A labeling space is an Euclidean space where coordinates are the edit costs. Through this model, we define a class of cost. A class of cost is a region in the labeling space that all the edit costs have the same optimal labeling. Moreover, we characterize the distance value through the labeling space. This new point of view of the edit distance gives us the opportunity of defining some interesting properties that are useful for a better understanding of the edit distance. Finally, we show the usefulness of these properties through some applications.