Current Issue : July - September Volume : 2020 Issue Number : 3 Articles : 5 Articles
Lubricating oils degrade into two main products: oxidation products and solid particles. Oxidation products, called varnish, of\nturbine oils for power generation have become a particularly serious problem in recent years. The first step in determining the\npotential to produce varnish is to determine the remaining life of the antioxidant in the oil, but even though turbine oil may have\nantioxidants of sufficient longevity, varnish problems still occur frequently. Accordingly, to prevent varnish, it is necessary to\ndiagnose oil oxidation products.............................
Urban rail transit is an effective way to deal with the problem of traffic congestion in major cities. Trains travel through dense\nresidential and commercial areas, providing convenient transportation while also result in vibration problems in the surrounding\nenvironment. Long-lasting vibrations result in disturbance to peopleâ??s sleep, malfunction of sensitive equipment, and even\ndamage to heritage buildings. Compared with elevated and tunnel sections, ground surface urban railway generates vibrations and\npropagates to the surroundings via a more direct path in the form of surface waves, which makes the environmental problem more\nprominent..............................
The accurate prediction of the remaining useful life (RUL) of rolling bearings is of great significance for a rational formulation of\nmaintenance strategies and the reduction of maintenance costs. According to the two-stage nonlinear degradation characteristics\nof rolling bearing operation, this paper proposes a prognosis model based on modified stochastic filtering. First, multiple features\nreextracted from the time domain, frequency domain, and complexity angles, and the baseline Gaussian mixture model (GMM) is\nestablished using the normal operating data after spectral regression. The Bayesian-inferred distance (BID) is used as a\nquantitative indicator to reflect the bearing performance degradation degree. Then, taking multiparameter fusion results as input,\nthe relationship between BID and remaining life is established by the two-stage stochastic filtering model to realize online dynamic\nremaining useful life prediction. The method in this paper overcomes the difficulty of accurately defining the failure threshold of\nrolling bearing. At the same time, it reduces the computational burden, avoiding the need of calculating the joint probability\ndistribution for high-dimensional data. Finally, the proposed method has been verified experimentally to have high precision and\nengineering application value....
The paper presents a framework for the seismic analysis of the coupled high-speed train-bridge with the isolation of friction\npendulum bearing (FPB). Taking the rail irregularities as systemâ??s self-excitation with the seismic as external excitation, the\nequation of motion of the train-bridge coupled system under earthquake is built up.........................
Friction during the hot extrusion of Inconel 625 superalloy tubes causes severe wear of the mold and plays a decisive role in the\nquality of the workpieces...............................
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