In order to obtain the entire continuous circumferential film pressure distribution of a water-lubricated rubber bearing with multiaxial grooves, and further to study the bearing properties, an experimental research was conducted. The wireless measurement scheme was proposed, which can make the measurement process simple, convenient, and accurate. The unique design of the shaft and the installation methods for the pressure sensors are described. The time-domain averaging (TDA) algorithm was presented to suppress the random noises of the film pressure signal. By contrastive analysis on experimental results, some bearing properties, and working mechanism have been found and demonstrated.
Sequencing of the KCNQ2 gene revealed that all 17 affected family members carried a heterozygous Gly-to-Val (G271V) mutation in the conserved pore region that resulted from a guanine-to-thymine transition in exon 5 of KCNQ2. The same mutation with a comparable localization in the KCNQ3 (G310V) gene has been found in BFNS patients. The same conserved amino acid was also found to be mutated in the KCNQ1 gene in a family with Long QT Syndrome.
An extended ultrasonic time-of-flight (TOF) method is proposed for measuring the thickness of lubricant film. Based on the spectrum analysis method of superimposed pulses, the extended TOF determines the travel time of ultrasonic wave and subsequently the film thickness in frequency domain. The method extends the measurable range of the original TOF method to the lubricant films of superimposed reflected pulses, which usually processed by the resonance model. The extended TOF gives another interpretation to the resonance phenomenon described by the resonance model. In theory and practice, the extended TOF integrates the resonance model and the original TOF method into one approach. This solved the problem that film thickness monitoring program needs to alter between time and frequency domains according to the changing of film thickness. A precision experimental apparatus was designed for verifying the correctness of the method. The lubricant films of different thickness were measured repeatedly and the measuring accuracy was analyzed.
When conducting ultrasonic measurements of the lubricant film thickness in sliding bearings with thin liners, the ultrasonic pulse reflected from the bearing liner–lubricant film interface will superimpose on the pulse reflected from the bearing substrate–liner interface. The thickness information of the lubricant film is contained in the reflected pulse from the liner–lubricant film interface. In this case, the film thickness could not be obtained directly from the superimposed reflected signals. The thin liner indicates that the thickness of the bearing liner is less than half the ultrasonic pulse width. Based on the spectrum analysis method of superimposed signals, a new method is proposed to measure the lubricant film thickness in sliding bearings with thin liners. The frequency-domain amplitude ratio between the echo component containing thickness information and the steady echo component from the bearing substrate–liner interface is extracted from the superimposed signal. The reflection coefficient of the liner–lubricant film interface is obtained by this amplitude ratio to determine the film thickness. The lubricant films of different thicknesses in a thin-liner thrust pad were measured in a high-precision experimental apparatus. The measurement results were compared with the known film thickness set by the experimental apparatus. In the thinner film region, the measurement results agreed well with the set film thickness. In the thicker film region, the mean values of the multiple measurement results represented the film thickness. The experimental results show that the method can be used to measure the lubricant film thickness in sliding bearings with thin liners.
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