A Stability Criterion for Parameter-Dependent Gyroscopic Systems

1999 ◽  
Vol 66 (3) ◽  
pp. 660-664 ◽  
Author(s):  
R. O. Hryniv ◽  
P. Lancaster ◽  
A. A. Renshaw
Keyword(s):  
Eigenvalue Problem ◽  
Stability Criterion ◽  
System Stability ◽  
Actual Computation ◽  
Design Changes ◽  
Engineering Problems ◽  
The Stability ◽  
Parameter Dependent ◽  
Gyroscopic Systems

A stability criterion for parameter-dependent gyroscopic systems is established and three examples are used to illustrate its application to typical engineering problems. In a number of practical situations, the criterion can be used to predict system stability with little actual computation and without solving any eigenvalue problem or approximating the eigenvalue locus. Thus, the criterion provides designers with a quick and accurate tool for assessing the stability consequences of potential design changes.

Chaotic Characteristic Analysis of Concrete Fracture System Based on Lyapunov Exponent Stability Criterion

2013 ◽  
Vol 423-426 ◽  
pp. 1105-1109
Author(s):  
Jun Wei Song
Keyword(s):  
Compressive Strength ◽  
Steady State ◽  
Stability Criterion ◽  
System Stability ◽  
Stress System ◽  
Characteristic Analysis ◽  
Chaotic State ◽  
Whole Process ◽  
Strain Stress ◽  
The Stability

According to the research on whole curves of strain-stress of concrete materials, the paper illustrates in evidence features of stages and shows that the discrete feature of curve often occurs in strain-softening stage. After chaotic dynamic analysis of testing datas, it presents that system of whole process of strain-stress evolves from ordered steady state to low chaotic state and then to high chaotic state along with increase of compressive strength. The linear relationship of strain-stress grows evident and the system evolves from strong ordered steady state to low chaos state. The strain-stress system before compressive strength peak is basically in weak chaotic state. Theis proposed to be the stability criterion of concrete features in different stress stages, and the is regarded as the representative value of the system stability degree. The calculation of example shows that the stability criterion definited by the proposed method is consistent with the actural situation.

Research on Lyapunov Exponent of Chaos Feature in Different Stress Stage of Concrete Joint System

2010 ◽  
Vol 143-144 ◽  
pp. 120-124 ◽  
Author(s):  
Jun Wei Song
Keyword(s):  
Compressive Strength ◽  
Steady State ◽  
Stability Criterion ◽  
System Stability ◽  
Stress System ◽  
Chaotic State ◽  
Whole Process ◽  
Strain Stress ◽  
The Stability ◽  
Relationship Of

: According to the research on whole curves of strain-stress of concrete materials, the paper illustrates in evidence features of stages and shows that the discrete feature of curve often occurs in strain-softening stage. After chaotic dynamic analysis of testing datas, it presents that system of whole process of strain-stress evolves from ordered steady state to low chaotic state and then to high chaotic state along with increase of compressive strength. The linear relationship of strain- stress grows evident and the system evolves from strong ordered steady state to low chaos state. The strain-stress system before compressive strength peak is basically in weak chaotic state. The is proposed to be the stability criterion of concrete features in different stress stages, and the is regarded as the representative value of the system stability degree. The calculation of example shows that the stability criterion definited by the proposed method is consistent with the actural situation.

CFD Analysis of a Canned Pump Rotor Considering an Annular Fluid With Axial Flow

2009 ◽  
Author(s):  
Alexandrina Untaroiu ◽  
Timothy W. Dimond ◽  
Paul E. Allaire ◽  
Richard Armentrout
Keyword(s):  
Axial Flow ◽  
System Stability ◽  
System Component ◽  
Fluid Inertia ◽  
Fluid Forces ◽  
Rotordynamic Coefficients ◽  
Design Changes ◽  
Rotor Bearing ◽  
Rotor Center ◽  
The Stability

Instability in rotor-bearing systems can lead to high levels of vibration, that can ultimately result in the destruction of rotating machines or lost production due to reduced speeds and flow rates. Thus, accurate characterization of instability drivers is vital in prediction of the stability of rotor-bearing-structural systems, allowing for design changes to reduce deleterious effects. These changes include alteration of the system component causing instability and alteration of the bearing design to improve the overall system stability. A source of destabilizing forces in vertical canned motor pumps arises from fluid-structure interaction (FSI) forces between the rotor can and the stator. In this paper, the FSI forces are modeled using an analysis of a long annular fluid filled region with an axial flow component. The model includes the effects of pre-swirl of the fluid entering the annulus. The rotor center static operating position is eccentric to the stator center due to manufacturing tolerances. The fluid forces are calculated using computational fluid dynamics (CFD) and are expressed in terms of equivalent stiffness, damping and fluid inertia (added mass) rotordynamic coefficients. The rotordynamic coefficients are identified using CFD by simulating non-synchronous perturbations of the rotor position and velocity around the static operating point. A separate set of simulations, which does not consider the effects of axial flow on the rotordynamic coefficients, are performed to facilitate direct comparison between the CFD predictions and the dynamic coefficients calculated using the bulk-flow method developed by Fritz.

Studies on Bilateral Impedance Control Method for Teleoperation Robot

2014 ◽  
Vol 602-605 ◽  
pp. 924-927
Author(s):  
Min Ying ◽  
Xin Gao ◽  
Si Yu Han ◽  
Han Xu Sun ◽  
Qing Xuan Jia
Keyword(s):  
Stability Condition ◽  
Stability Criterion ◽  
Absolute Stability ◽  
Force Feedback ◽  
Control Method ◽  
Impedance Control ◽  
Tracking Performance ◽  
System Stability ◽  
Pd Control ◽  
The Stability

The bilateral PD control method for teleoperation robot has some defects, such as poor tracking performance and force feedback performance. This paper, based on traditional bilateral PD control method, adds an impedance controller to the master and the slave, and deduces the stability condition according to the absolute stability criterion. The simulation shows that this method can assure the system stability and improve tracking performance and force feedback performance.

Stability of Ring-Type MEMS Gyroscopes Subjected to Stochastic Angular Speed Fluctuation

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Samuel F. Asokanthan ◽  
Soroush Arghavan ◽  
Mohamed Bognash
Keyword(s):  
Angular Velocity ◽  
Degrees Of Freedom ◽  
Microelectromechanical Systems ◽  
Damping Ratio ◽  
Operating Conditions ◽  
System Stability ◽  
System Response ◽  
Ring Type ◽  
Mems Gyroscopes ◽  
The Stability

Effect of stochastic fluctuations in angular velocity on the stability of two degrees-of-freedom ring-type microelectromechanical systems (MEMS) gyroscopes is investigated. The governing stochastic differential equations (SDEs) are discretized using the higher-order Milstein scheme in order to numerically predict the system response assuming the fluctuations to be white noise. Simulations via Euler scheme as well as a measure of largest Lyapunov exponents (LLEs) are employed for validation purposes due to lack of similar analytical or experimental data. The response of the gyroscope under different noise fluctuation magnitudes has been computed to ascertain the stability behavior of the system. External noise that affect the gyroscope dynamic behavior typically results from environment factors and the nature of the system operation can be exerted on the system at any frequency range depending on the source. Hence, a parametric study is performed to assess the noise intensity stability threshold for a number of damping ratio values. The stability investigation predicts the form of threshold fluctuation intensity dependence on damping ratio. Under typical gyroscope operating conditions, nominal input angular velocity magnitude and mass mismatch appear to have minimal influence on system stability.

scholarly journals Application of Deep Reinforcement Learning to Predict Shaft Deformation Considering Hull Deformation of Medium-Sized Oil/Chemical Tanker

2021 ◽  
Vol 9 (7) ◽  
pp. 767
Author(s):  
Shin-Pyo Choi ◽  
Jae-Ung Lee ◽  
Jun-Bum Park
Keyword(s):  
Reinforcement Learning ◽  
Reaction Force ◽  
Measurement Data ◽  
System Stability ◽  
Main Bearing ◽  
Shaft System ◽  
Novel Approach ◽  
Design Changes ◽  
Prediction Techniques ◽  
Shaft Deformation

The enlargement of ships has increased the relative hull deformation owing to draft changes. Moreover, design changes such as an increased propeller diameter and pitch changes have occurred to compensate for the reduction in the engine revolution and consequent ship speed. In terms of propulsion shaft alignment, as the load of the stern tube support bearing increases, an uneven load distribution occurs between the shaft support bearings, leading to stern accidents. To prevent such accidents and to ensure shaft system stability, a shaft system design technique is required in which the shaft deformation resulting from the hull deformation is considered. Based on the measurement data of a medium-sized oil/chemical tanker, this study presents a novel approach to predicting the shaft deformation following stern hull deformation through inverse analysis using deep reinforcement learning, as opposed to traditional prediction techniques. The main bearing reaction force, which was difficult to reflect in previous studies, was predicted with high accuracy by comparing it with the measured value, and reasonable shaft deformation could be derived according to the hull deformation. The deep reinforcement learning technique in this study is expected to be expandable for predicting the dynamic behavior of the shaft of an operating vessel.

Stability and Natural Characteristics of a Supported Beam

2011 ◽  
Vol 338 ◽  
pp. 467-472 ◽  
Author(s):  
Ji Duo Jin ◽  
Xiao Dong Yang ◽  
Yu Fei Zhang
Keyword(s):  
Eigenvalue Problem ◽  
Boundary Conditions ◽  
Axial Force ◽  
Critical Values ◽  
Rotational Spring ◽  
Analytical Expression ◽  
The Stability ◽  
Spring Constants ◽  
Critical Axial Force ◽  
Natural Characteristics

The stability, natural characteristics and critical axial force of a supported beam are analyzed. The both ends of the beam are held by the pinned supports with rotational spring constraints. The eigenvalue problem of the beam with these boundary conditions is investigated firstly, and then, the stability of the beam is analyzed using the derived eigenfuntions. According to the analytical expression obtained, the effect of the spring constants on the critical values of the axial force is discussed.

Design of Electrostatic Precipitator Power System Based on Auto Disturbance Rejection Controller

2013 ◽  
Vol 846-847 ◽  
pp. 190-194
Author(s):  
Shu Jun Yin ◽  
Xue Ren Li ◽  
Ji Geng Luo
Keyword(s):  
Power Supply ◽  
Disturbance Rejection ◽  
Power Supply System ◽  
Electrostatic Precipitator ◽  
Supply System ◽  
System Stability ◽  
Engineering Practice ◽  
Single Chip ◽  
High Voltage Power Supply ◽  
The Stability

The paper designs a three-phase high voltage power supply system based on active disturbance rejection controller which make single-chip microcomputer ATmega128 as the main control chip and the system improve the stability and control precision of dust removing power. Engineering practice shows that, the DC power supply system has the advantages of convenient operation, high work efficiency, system stability.

Intrinsic Thermal Stability of Anisotropic Thin-Film Superconductors

1990 ◽  
Vol 112 (1) ◽  
pp. 10-15 ◽  
Author(s):  
M. I. Flik ◽  
C. L. Tien
Keyword(s):  
Thin Film ◽  
Thermal Stability ◽  
Stability Criterion ◽  
High Temperature Superconductors ◽  
Stability Criteria ◽  
Anisotropic Thermal Conductivity ◽  
Operating Current ◽  
Released Energy ◽  
The Stability ◽  
Thermal Stability Of

Intrinsic thermal stability denotes a situation where a superconductor can carry the operating current without resistance at all times after the occurrence of a localized release of thermal energy. This novel stability criterion is different from the cryogenic stability criteria for magnets and has particular relevance to thin-film superconductors. Crystals of ceramic high-temperature superconductors are likely to exhibit anisotropic thermal conductivity. The resultant anisotropy of highly oriented films of superconductors greatly influences their thermal stability. This work presents an analysis for the maximum operating current density that ensures intrinsic stability. The stability criterion depends on the amount of released energy, the Biot number, the aspect ratio, and the ratio of the thermal conductivities in the plane of the film and normal to it.

The flow of a micropolar liquid layer down an inclined plane

1968 ◽  
Vol 64 (2) ◽  
pp. 513-526 ◽  
Author(s):  
A. J. Willson
Keyword(s):  
Thin Films ◽  
Steady State ◽  
Liquid Layer ◽  
Stability Criterion ◽  
Long Waves ◽  
Inclined Plane ◽  
The Stability ◽  
Micropolar Liquid

AbstractConsideration is given to the flow of a micropolar liquid down an inclined plane. The steady state is analysed and Yih's technique is employed in an investigation of the stability of this flow with respect to long waves. Detailed calculations are given for thin films and it is shown that the micropolar properties of the liquid play an important role in the stability criterion.

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