The Determination of Squeeze Film Dynamic Coefficients From Transient Two-Dimensional Experimental Data

1990 ◽  
Vol 112 (2) ◽  
pp. 288-296 ◽  
Author(s):  
J. B. Roberts ◽  
J. Ellis ◽  
A. Hosseini Sianaki
Keyword(s):  
Experimental Data ◽  
Simulated Data ◽  
Degree Of Freedom ◽  
Squeeze Film ◽  
Two Dimensional ◽  
Computationally Efficient ◽  
Response Data ◽  
Lumped Parameter ◽  
Experimental Trials ◽  
State Variable Filter

A state variable filter (SVF) method of identifying parameters in lumped-parameter systems is extended to accommodate multi-degree-of-freedom problems. The method is computationally efficient and can be used with both transient and forced squeeze-film response data. In this paper the method is successfully applied to the analysis of transient simulated data both with and without signal noise. Finally the method is shown applied in the analysis of two-dimensional transient experimental data from a squeeze-film bearing rig. The identified results for the dynamic film coefficients compare well with results from earlier single-degree-of-freedom experimental trials.

A Comparison of Identification Methods for Estimating Squeeze-Film Damper Coefficients

1988 ◽  
Vol 110 (1) ◽  
pp. 119-127 ◽  
Author(s):  
J. Ellis ◽  
J. B. Roberts ◽  
A. Hosseini Sianaki
Keyword(s):  
A Priori ◽  
Simulated Data ◽  
Experimental Tests ◽  
Forced Response ◽  
Squeeze Film ◽  
Filter Method ◽  
Single Degree Of Freedom ◽  
Response Data ◽  
State Variable ◽  
State Variable Filter

The problem of identifying the dynamic coefficients relating to inertia, damping, and stiffness, in a single degree of freedom model of squeeze-film behavior, is discussed. It is demonstrated that two methods—referred to as “invariant imbedding” and “state variable filter”—are applicable, and that both yield a recursive scheme for sequentially estimating all three coefficients. The methods are compared through an analysis of simulated data, where the coefficient values are known a-priori. This is followed by a presentation of some typical results obtained from experimental tests, using both transient and forced response data. The comparisons indicate that the state variable filter method is much superior, with respect to both computational efficiency and accuracy.

An Adaptive Tracking Algorithm for Convection in Simulated and Remote Sensing Data

2021 ◽  
Vol 60 (4) ◽  
pp. 513-526
Author(s):  
Bhupendra A. Raut ◽  
Robert Jackson ◽  
Mark Picel ◽  
Scott M. Collis ◽  
Martin Bergemann ◽  
...  
Keyword(s):  
Simulated Data ◽  
Remote Sensing Data ◽  
Life Cycles ◽  
Tracking Algorithm ◽  
Two Dimensional ◽  
Computationally Efficient ◽  
Convective Systems ◽  
Object Based ◽  
Modular Platform ◽  
Convective Cells

AbstractA robust and computationally efficient object tracking algorithm is developed by incorporating various tracking techniques. Physical properties of the objects, such as brightness temperature or reflectivity, are not considered. Therefore, the algorithm is adaptable for tracking convection-like features in simulated data and remotely sensed two-dimensional images. In this algorithm, a first guess of the motion, estimated using the Fourier phase shift, is used to predict the candidates for matching. A disparity score is computed for each target–candidate pair. The disparity also incorporates overlapping criteria in the case of large objects. Then the Hungarian method is applied to identify the best pairs by minimizing the global disparity. The high-disparity pairs are unmatched, and their target and candidate are declared expired and newly initiated objects, respectively. They are tested for merger and split on the basis of their size and overlap with the other objects. The sensitivity of track duration is shown for different disparity and size thresholds. The paper highlights the algorithm’s ability to study convective life cycles using radar and simulated data over Darwin, Australia. The algorithm skillfully tracks individual convective cells (a few pixels in size) and large convective systems. The duration of tracks and cell size are found to be lognormally distributed over Darwin. The evolution of size and precipitation types of isolated convective cells is presented in the Lagrangian perspective. This algorithm is part of a vision for a modular platform [viz., TINT is not TITAN (TINT) and Tracking and Object-Based Analysis of Clouds (tobac)] that will evolve into a sustainable choice to analyze atmospheric features.

An Experimental Hand/Arm Model for Human Interaction With a Telemanipulation System

2001 ◽  
Author(s):  
John E. Speich ◽  
Liang Shao ◽  
Michael Goldfarb
Keyword(s):  
Experimental Data ◽  
Second Order ◽  
Degree Of Freedom ◽  
Human Interaction ◽  
Haptic Interfaces ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Lumped Parameter ◽  
Mass Spring ◽  
System 1

Abstract This paper describes the development of a linear single degree-of-freedom lumped-parameter hand/arm model for the operator of a telemanipulaton system. The model form and parameters were determined from experimental data taken from a single degree-of-freedom telemanipulation system. Typically, the human is modeled as a second order mass-spring-damper system [1, 2]. The model developed in this paper, however, includes an additional spring and damper to better approximate the dynamics of the human while interacting with the manipulator. This model can be used in the design and simulation of control architectures for telemanipulation systems and haptic interfaces.

Experimental and Analytical Study of Pantograph Dynamics

1991 ◽  
Vol 113 (2) ◽  
pp. 242-247 ◽  
Author(s):  
W. Seering ◽  
K. Armbruster ◽  
C. Vesely ◽  
D. Wormley
Keyword(s):  
Experimental Data ◽  
Dynamic Response ◽  
Coulomb Friction ◽  
Close Agreement ◽  
Analytical Study ◽  
Model Performance ◽  
Nonlinear Effects ◽  
Variable Stiffness ◽  
Response Data ◽  
Lumped Parameter

A nonlinear, lumped parameter pantograph model including geometric and coulomb friction nonlinearities and variable stiffness has been developed. The model performance has been compared with experimental dynamic response data measured on a prototype pantograph. Responses of the model and the experimental data including subharmonic and harmonic resonances are in close agreement for motions excited by comparable forcing functions for input frequencies of 0 to 12 Hz. The model has been used to identify the primary parameters and nonlinear effects which influence dynamic pantograph performance.

The Complete Determination of Squeeze-Film Linear Dynamic Coefficients From Experimental Data

1990 ◽  
Vol 112 (4) ◽  
pp. 712-724 ◽  
Author(s):  
J. Ellis ◽  
J. B. Roberts ◽  
A. Hosseini Sianaki
Keyword(s):  
Experimental Data ◽  
Initial Conditions ◽  
Parametric Identification ◽  
Squeeze Film ◽  
Time Interval ◽  
Cross Terms ◽  
Complete Set ◽  
Data Tables ◽  
Linearized Model ◽  
State Variable Filter

This paper describes the use of the State Variable Filter (SVF) method of parametric identification to estimate the complete set of twelve linear hydrodynamic coefficients for a squeeze-film bearing system. Simulated force and displacement data are used to assess the algorithm and issues such as noise tolerance, the influence of sample time interval and input signal complexity are investigated. Real experimental data from a squeeze-film rig are processed by the SVF method and the technique used to derive linearized model coefficients is explained. For the first time, all twelve coefficients in the general linear model are estimated from experimental data. Tables and graphs are used to present the coefficient values. Sixteen parameters (including four parameters relating to initial conditions) are identified in each experiment. The direct coefficients show the same trends and orders of magnitude reported in earlier and simpler tests, relating to a single-degree-of-freedom system. The damping cross-terms are found to be virtually zero whereas the inertial and stiffness cross-terms appear to be significantly nonzero.

Numerical Solution of the General Two-Dimensional Inverse Heat Conduction Problem (IHCP)

1997 ◽  
Vol 119 (1) ◽  
pp. 38-45 ◽  
Author(s):  
A. M. Osman ◽  
K. J. Dowding ◽  
J. V. Beck
Keyword(s):  
Experimental Data ◽  
Heat Conduction ◽  
Heat Conduction Problem ◽  
Regularization Parameter ◽  
Simulated Data ◽  
Inverse Heat Conduction Problem ◽  
Transient Temperature ◽  
Two Dimensional ◽  
Inverse Heat Conduction ◽  
Temperature Dependent

This paper presents a method for calculating the heat flux at the surface of a body from experimentally measured transient temperature data, which has been called the inverse heat conduction problem (IHCP). The analysis allows for two-dimensional heat flow in an arbitrarily shaped body and orthotropic temperature dependent thermal properties. A combined function specification and regularization method is used to solve the IHCP with a sequential-in-time concept used to improve the computational efficiency. To enhance the accuracy, the future information used in the sequential-in-time method and the regularization parameter are variable during the analysis. An example using numerically simulated data is presented to demonstrate the application of the method. Finally, a case using actual experimental data is presented. For this case, the boundary condition was experimentally measured and hence, it was known. A good comparison is demonstrated between the known and estimated boundary conditions for the analysis of the numerical, as well as the experimental data.

Modelling of Moisture Movement in Wood during Outdoor Storage

2001 ◽  
Vol 6 (2) ◽  
pp. 3-14 ◽  
Author(s):  
R. Baronas ◽  
F. Ivanauskas ◽  
I. Juodeikienė ◽  
A. Kajalavičius
Keyword(s):  
Experimental Data ◽  
Finite Difference ◽  
Climatic Conditions ◽  
Two Dimensional ◽  
Moisture Movement ◽  
Finite Difference Technique ◽  
Long Term Storage ◽  
Space Formulation ◽  
Term Storage

A model of moisture movement in wood is presented in this paper in a two-dimensional-in-space formulation. The finite-difference technique has been used in order to obtain the solution of the problem. The model was applied to predict the moisture content in sawn boards from pine during long term storage under outdoor climatic conditions. The satisfactory agreement between the numerical solution and experimental data was obtained.

Sign in / Sign up

Export Citation Format

Share Document