scholarly journals A new method for the estimation of bearing health state and remaining useful life based on the moving average cross-correlation of power spectral density

2020 ◽  
Vol 139 ◽  
pp. 106617 ◽  
Author(s):  
Lang Xu ◽  
Paolo Pennacchi ◽  
Steven Chatterton
Keyword(s):  
Spectral Density ◽  
Power Spectral Density ◽  
Cross Correlation ◽  
Moving Average ◽  
Remaining Useful Life ◽  
New Method ◽  
Health State ◽  
Power Spectral ◽  
Useful Life

scholarly journals In-Depth Investigation of Statistical and Physicochemical Properties on the Field Study of the Intermittent Filling of Large Water Tanks

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Do-Hwan Kim ◽  
Doo Yong Choi ◽  
Taeho Choi ◽  
Zong Woo Geem
Keyword(s):  
Spectral Density ◽  
Power Spectral Density ◽  
Field Measurement ◽  
Cross Correlation ◽  
Fine Particles ◽  
Normal Operation ◽  
Particle Count ◽  
Power Spectral ◽  
Flow Pressure ◽  
Water Tanks

Large-demand customers, generally high-density dwellings and buildings, have dedicated ground or elevated water tanks to consistently supply drinking water to residents. Online field measurement for Nonsan-2 district meter area demonstrated that intermittent replenishment from large-demand customers could disrupt the normal operation of a water distribution system by taking large quantities of water in short times when filling the tanks from distribution mains. Based on the previous results of field measurement for hydraulic and water quality parameters, statistical analysis is performed for measured data in terms of autocorrelation, power spectral density, and cross-correlation. The statistical results show that the intermittent filling interval of 6.7 h and diurnal demand pattern of 23.3 h are detected through autocorrelation analyses, the similarities of the flow-pressure and the turbidity-particle count data are confirmed as a function of frequency through power spectral density analyses, and a strong cross-correlation is observed in the flow-pressure and turbidity-particle count analyses. In addition, physicochemical results show that the intermittent refill of storage tank from large-demand customers induces abnormal flow and pressure fluctuations and results in transient-induced turbid flow mainly composed of fine particles ranging within 2–4 μm and constituting Fe, Si, and Al.

scholarly journals Rotor Blades Diagnosis Method Based on Differences in Phase Shifts

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Rafał Grądzki ◽  
Paweł Lindstedt ◽  
Zbigniew Kulesza ◽  
Błażej Bartoszewicz
Keyword(s):  
Phase Shift ◽  
Spectral Density ◽  
Power Spectral Density ◽  
Cross Correlation ◽  
Technical Condition ◽  
Rotor Blades ◽  
Density Functions ◽  
Power Spectral ◽  
Spectral Density Functions ◽  
Diagnosis Method

In this work, an innovative diagnosis method of rotor blades is presented. A measurement signal of blade tip displacement is divided into two observation zones, in which two peaks of an additional template signal are introduced. Cross-correlation and power spectral density functions of the measurement and template signals in these two distinct zones are calculated. Next, the phase shift between the two cross-correlation functions is obtained by calculating the ratio of the two power spectral density functions. The changes in parameters of an analytical description of this phase shift are used to determine a distinct and easy-to-analyze image of the technical condition of the tested blade. A graphical portrait indicating the technical condition of all blades in the annulus is developed. Although not directly measured, environmental signals (e.g., external disturbances and sensor’s noise) affecting the diagnostic process are included in the method. It is demonstrated that, by using the proposed signal processing technique, a negative influence of these disturbances is eliminated and the reliability of the machine technical condition indications is improved. The approach is demonstrated using experimental results of turbine engine blade displacements. High effectiveness of the method and measurement equipment has been confirmed in a wide range of analyzed tip-timing results obtained in different periods of the measurement process.

scholarly journals Construction and tests of the research stand with built-in correctors for the detection of gas outflow from long pipelines

2018 ◽  
Vol 182 ◽  
pp. 01021
Author(s):  
Karol Golak ◽  
Paweł Lindstedt ◽  
Błażej Bartoszewicz
Keyword(s):  
Spectral Density ◽  
Power Spectral Density ◽  
Mass Flow ◽  
Gas Pipeline ◽  
New Method ◽  
Precise Localization ◽  
Intensity Measurements ◽  
Power Spectral ◽  
Gas Leaks ◽  
Membrane Displacement

The localization and identification of small gas leaks from a damaged gas pipeline is a very important but at the same time problematic and difficult process to carry out. Quick identification, estimation and precise localization of the leak leads to minimizing the financial and equipment losses resulting from damage. The most commonly used continuous internal methods of leak identification are based on pressure and mass intensity measurements flow at various places in the pipeline. The article presents a description of the construction of a test stand characterized by the correctors built in it and the examples of the signals obtained from its tests for different values of simulated leaks. The results obtained will be used to develop a new method for identifying and locating leakages from long pipelines. This method is based on the cross power spectral density of measured pipeline standard signals (pressure and mass flow) and the membrane displacement signals delivered from the test equipment (correctors) connected to the system.

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