An Experimental Method for the Determination of Journal-Bearing Stability Parameters. Part 2: Experiment

1979 ◽  
Vol 21 (3) ◽  
pp. 187-196 ◽  
Author(s):  
J. E. L. Simmons
Keyword(s):  
Experimental Method ◽  
Journal Bearing ◽  
Experimental Results ◽  
Air Bearing ◽  
Stability Parameters ◽  
Basic Principles ◽  
Underlying Theory ◽  
Stability Data ◽  
The Stability

The design of a flexibly mounted journal-bearing apparatus is described, and it is shown how the experimental results may be used to generate stability charts for design. For reasons of simplicity in demonstrating the basic principles, this work has been carried out using a plain circular air bearing. The underlying theory, however, is common to all journal-bearing systems, and it is intended to extend the experimental method to liquid-lubricated bearings and non-circular profiles. In addition to the stability data which have been obtained, the apparatus has enabled a detailed study of the phenomenon of whirl cessation.

An Experimental Method for the Determination of Journal-Bearing Stability Parameters. Part 1: Theory

1979 ◽  
Vol 21 (3) ◽  
pp. 179-185 ◽  
Author(s):  
H. Marsh ◽  
J. E. L. Simmons
Keyword(s):  
Journal Bearing ◽  
Eccentricity Ratio ◽  
Stability Parameters ◽  
Operating Condition ◽  
Stable Operating ◽  
System Information ◽  
The Stability ◽  
Bearing System ◽  
Steady State Performance

In the design of a rotor-bearing system, information is usually available on the steady-state performance of the bearing. The designer can estimate the eccentricity ratio and attitude angle for any operating condition, but there is often little or no information which can be used to predict whether or not this is a stable operating condition. This paper describes the basic theory of bearing stability and shows how this can be used to help in the design of a novel apparatus for determining the stability parameters of any journal-bearing system.

Determination of Stability Derivatives by Impulse-Response Techniques

1977 ◽  
Vol 14 (02) ◽  
pp. 265-275
Author(s):  
Carl A. Scragg
Keyword(s):  
Memory Effect ◽  
Impulse Response ◽  
Traditional Method ◽  
Equations Of Motion ◽  
Experimental Results ◽  
Regular Motion ◽  
Stability Derivatives ◽  
The Stability ◽  
Derivatives Of

This paper presents a new method of experimentally determining the stability derivatives of a ship. Using a linearized set of the equations of motion which allows for the presence of a memory effect, the response of the ship to impulsive motions is examined. This new technique is compared with the traditional method of regular-motion tests and experimental results are presented for both methods.

scholarly journals APPLICATION OF KINEMATIC STABILITY ANALYSIS IN DETERMINING RATIONAL DESIGN PARAMETERS OF CAREER STEPS

2021 ◽  
Vol 445 (1) ◽  
pp. 135-143
Author(s):  
S. А. Sedina ◽  
G. B. Abdikarimova ◽  
A. A. Altayeva ◽  
N. D. Rakhimov
Keyword(s):  
Rational Design ◽  
Open Pit ◽  
Design Parameters ◽  
Optimal Parameters ◽  
Stability Parameters ◽  
Failure Patterns ◽  
Safe State ◽  
Rational Design Parameters ◽  
The Stability

The main factor that determines the stability of the pit benches in rocky and semi-rocky rocks is geological and structural since potential collapse prisms of a particular configuration are formed by differently oriented ruptured faults (cracks) with certain spatial relationships between themselves and the pit surface. Evaluation of possible planar, wedge-shaped, and overturning collapses of individual benches is carried out by analyzing the parameters of structural disturbances identified within the rock mass of the studied section of the open pit relative to the orientation of open pit edges. The article presents the results of the analysis of the kinematic stability of the optimal parameters of the benches on the example of the Kurzhunkul open pit, which ensures their stability on the limiting contour. A sequence of actions is proposed for determining the stability parameters of rock benches in a quarry. Performing a kinematic analysis based on the identified systems of cracks allows us to determine the probable failure patterns of the slopes of the benches and select the calculation schemes for their stability to substantiate their optimal parameters and make decisions on their stabilization. Geological and structural zoning of the quarry space according to this method allows analyzing the holding capacity of safety berms to control detected collapses, to highlight benches that need to be brought into a safe state with the determination of their stable parameters, and to recommend options for optimizing the design profile.

Effects of Synchronous Vibration of Bearing on Stability of Externally Pressurized Air Journal Bearings

1999 ◽  
Vol 121 (4) ◽  
pp. 830-835 ◽  
Author(s):  
Jeong-Bae Lee ◽  
Kyung-Woong Kim
Keyword(s):  
Steady State ◽  
Phase Difference ◽  
High Speed ◽  
Control Algorithm ◽  
Journal Bearing ◽  
Stability Limit ◽  
Air Bearing ◽  
Synchronous Motion ◽  
Maximum Stability ◽  
The Stability

An active control of bearing is proposed as a new method to improve the stability characteristics of the externally pressurized air journal bearing and the results of numerical investigations of the stability characteristics of the actively controlled air journal bearing are presented. The synchronous control, where the bearing center whirls with the same frequency as the journal center with respect to the position in the steady state, is proposed as a control algorithm of the active air bearing. The step jump method is used to calculate the locus of the journal center which whirls or vibrates relative to the whirling bearing. The stability characteristics of the high speed rotor supported by actively controlled bearing system for zero steady-state eccentricity are investigated for various phase difference between the bearing and journal. It is shown that the stability of the air bearing can be greatly increased by the controlled synchronous motion of the bearing, and there is an optimum phase difference, which gives the maximum stability limit of the system.

scholarly journals Running Characteristics of Aerodynamic Bearing with Self-Lifting Capability at Low Rotational Speed

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Tadeusz Adam Stolarski
Keyword(s):  
Fourier Transform ◽  
Journal Bearing ◽  
Static Model ◽  
The Self ◽  
Experimental Results ◽  
Squeeze Film ◽  
Film Pressure ◽  
Squeeze Film Effect ◽  
Time Marching ◽  
The Stability

An aerodynamic journal bearing that is capable of self-generating squeeze-film pressure is presented and its dynamic characteristics investigated numerically and experimentally. A numerical method based on a time-marching static model was applied to assess the orbit trajectory path of the rotor upon a perturbation. Experimental results were obtained to validate the effect of the self-generated squeeze-film pressure on the stability of the rotor. Analyzing the Fast Fourier Transform (FFT) responses of the rotor orbits enabled identification of self-excited whirling instabilities. Both numerical and experimental results showed that increasing the squeeze-film effect of the bearing could raise the threshold speed of instability.

Determining the Norton’s Equivalent Model of Distribution System with Distributed Generation (DG) for Stability Analysis

2019 ◽  
Vol 12 (2) ◽  
pp. 190-198
Author(s):  
Sunny Katyara ◽  
Lukasz Staszewski ◽  
Faheem Akhtar Chachar
Keyword(s):  
Distributed Generation ◽  
Normal Condition ◽  
Distribution System ◽  
Distribution Networks ◽  
Equivalent Model ◽  
Stability Factor ◽  
Matlab Simulation ◽  
The Stability ◽  
Stability Issues

Background: Since the distribution networks are passive until Distributed Generation (DG) is not being installed into them, the stability issues occur in the distribution system after the integration of DG. Methods: In order to assure the simplicity during the calculations, many approximations have been proposed for finding the system’s parameters i.e. Voltage, active and reactive powers and load angle, more efficiently and accurately. This research presents an algorithm for finding the Norton’s equivalent model of distribution system with DG, considering from receiving end. Norton’s model of distribution system can be determined either from its complete configuration or through an algorithm using system’s voltage and current profiles. The algorithm involves the determination of derivative of apparent power against the current (dS/dIL) of the system. Results: This work also verifies the accuracy of proposed algorithm according to the relative variations in the phase angle of system’s impedance. This research also considers the varying states of distribution system due to switching in and out of DG and therefore Norton’s model needs to be updated accordingly. Conclusion: The efficacy of the proposed algorithm is verified through MATLAB simulation results under two scenarios, (i) normal condition and (ii) faulty condition. During normal condition, the stability factor near to 1 and change in dS/dIL was near to 0 while during fault condition, the stability factor was higher than 1 and the value of dS/dIL was away from 0.

Synthesis and solvatochromic studies of 2- amino-3-phenolazo1-(4-sulfophenyl)-3-methyi-5-pyrozolone and use it for the determination of trace amount of Nickel (II) in blood samples

2016 ◽  
Vol 5 (10) ◽  
pp. 4920
Author(s):  
Amar M. Ali ◽  
Hussain. J. Mohammed*
Keyword(s):  
Stability Constant ◽  
Trace Amount ◽  
Benzenesulfonic Acid ◽  
Determination Method ◽  
Blood Samples ◽  
Determination Of Nickel ◽  
Normal Human ◽  
The Stability ◽  
Normal Human Blood

A new, simple, sensitive and rapid spectrophotometric method is proposed for the determination of trace amount of Nickel (II). The method is based on the formation of a 1:2 complex with 4-(4-((2-hydroxy-6-nitrophenyl) diazenyl) -3-methyl-5-oxo-2, 5-dihydro-1H-pyrazol-1-yl) benzenesulfonic acid (2-ANASP) as a new reagent is developed. The complex has a maximum absorption at 516 nm and εmax of 1. 84 X 105 L. mol-1. cm-1. A linear correlation (0. 25 – 4. 0μg. ml-1) was found between absorbance at λmax and concentration. The accuracy and reproducibility of the determination method for various known amounts of Nickel (II) were tested. The results obtained are both precise (RSD was 1. 2 %) and accurate (relative error was 0. 787 %). The effect of diverse ions on the determination of Nickel (II) to investigate the selectivity of the method were also studied. The stability constant of the product was 0. 399 X 106 L. mol-1. The proposed method was successfully applied to the analysis of diabetes blood and normal human blood. 

Determination of Charge Coefficient of Piezoelectric Films Using a Combined Finite Element Model and Dynamic Loading Technique

2020 ◽  
Vol 835 ◽  
pp. 229-242
Author(s):  
Oboso P. Bernard ◽  
Nagih M. Shaalan ◽  
Mohab Hossam ◽  
Mohsen A. Hassan
Keyword(s):  
Finite Element ◽  
Dynamic Loading ◽  
Material Properties ◽  
Accurate Determination ◽  
Substrate Material ◽  
Experimental Results ◽  
Piezoelectric Composite ◽  
Piezoelectric Film ◽  
Piezoelectric Charge

Accurate determination of piezoelectric properties such as piezoelectric charge coefficients (d33) is an essential step in the design process of sensors and actuators using piezoelectric effect. In this study, a cost-effective and accurate method based on dynamic loading technique was proposed to determine the piezoelectric charge coefficient d33. Finite element analysis (FEA) model was developed in order to estimate d33 and validate the obtained values with experimental results. The experiment was conducted on a piezoelectric disc with a known d33 value. The effect of measuring boundary conditions, substrate material properties and specimen geometry on measured d33 value were conducted. The experimental results reveal that the determined d33 coefficient by this technique is accurate as it falls within the manufactures tolerance specifications of PZT-5A piezoelectric film d33. Further, obtained simulation results on fibre reinforced and particle reinforced piezoelectric composite were found to be similar to those that have been obtained using more advanced techniques. FE-results showed that the measured d33 coefficients depend on measuring boundary condition, piezoelectric film thickness, and substrate material properties. This method was proved to be suitable for determination of d33 coefficient effectively for piezoelectric samples of any arbitrary geometry without compromising on the accuracy of measured d33.

scholarly journals Determination of Objective Weights Using a New Method Based on the Removal Effects of Criteria (MEREC)

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 525 ◽  
Author(s):  
Mehdi Keshavarz-Ghorabaee ◽  
Maghsoud Amiri ◽  
Edmundas Kazimieras Zavadskas ◽  
Zenonas Turskis ◽  
Jurgita Antucheviciene
Keyword(s):  
Essential Elements ◽  
New Method ◽  
Multi Criteria Decision Making ◽  
Analysis Of Means ◽  
Simulation Based ◽  
Criteria Weights ◽  
The Stability ◽  
Computational Analyses ◽  
Weighting Methods

The weights of criteria in multi-criteria decision-making (MCDM) problems are essential elements that can significantly affect the results. Accordingly, researchers developed and presented several methods to determine criteria weights. Weighting methods could be objective, subjective, and integrated. This study introduces a new method, called MEREC (MEthod based on the Removal Effects of Criteria), to determine criteria’ objective weights. This method uses a novel idea for weighting criteria. After systematically introducing the method, we present some computational analyses to confirm the efficiency of the MEREC. Firstly, an illustrative example demonstrates the procedure of the MEREC for calculation of the weights of criteria. Secondly, a comparative analysis is presented through an example for validation of the introduced method’s results. Additionally, we perform a simulation-based analysis to verify the reliability of MEREC and the stability of its results. The data of the MCDM problems generated for making this analysis follow a prevalent symmetric distribution (normal distribution). We compare the results of the MEREC with some other objective weighting methods in this analysis, and the analysis of means (ANOM) for variances shows the stability of its results. The conducted analyses demonstrate that the MEREC is efficient to determine objective weights of criteria.

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