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.

The Experimental Determination of Squeeze-Film Dynamic Coefficients Using the State Variable Filter Method of Parametric Identification

1989 ◽  
Vol 111 (2) ◽  
pp. 252-259 ◽  
Author(s):  
J. Ellis ◽  
J. B. Roberts ◽  
M. D. Ramli
Keyword(s):  
Parametric Identification ◽  
Squeeze Film ◽  
Filter Method ◽  
State Variable ◽  
Dynamic Coefficients ◽  
Low Weight ◽  
State Variable Filter ◽  
Film Stiffness ◽  
Forced Excitation

The state variable filter method of parametric identification is applied in the determination of squeeze-film dynamic coefficients from forced excitation tests on an experimental rig. The experimental squeeze-film damper had a centralizing spring, a central circumferential oil feed groove, and no end seals. Forced excitation tests are recorded at various journal support system natural frequencies and at different journal eccentricities. From these tests, estimates of the direct squeeze-film damping, stiffness and inertial coefficients are derived and presented. These results are shown to be in good agreement with results recently obtained using an independent frequency domain technique. The experimental damping and inertial coefficients were found to be considerably larger than values predicted by conventional short-bearing theory, but relatively insensitive to the support system’s natural frequency (and the forcing frequency) for most of the range investigated. The fluid film stiffness coefficient values at low values of the system’s natural frequency agreed with results from static stiffness tests. Two geometrically identical journals were used, one of steel and one of a low-weight, magnesium alloy. The use of the low weight journal markedly reduced the scatter in the inertial and film stiffness coefficients.

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.

МАТЕМАТИЧЕСКОЕ МОДЕЛИРОВАНИЕ ДИНАМИКИ МИНЕРАЛЬНОГО ПИТАНИЯ РАСТЕНИЙ В СИСТЕМЕ «УДОБРЕНИЕ-ПОЧВА-РАСТЕНИЕ»

2020 ◽  
Vol 65 (6) ◽  
pp. 1219-1229
Author(s):  
В.А. Четырбоцкий ◽  
◽  
А.Н. Четырбоцкий ◽  
Б.В. Левин ◽  
◽  
...  
Keyword(s):  
Experimental Data ◽  
Temporal Dynamics ◽  
Plant Biomass ◽  
Environmental Parameters ◽  
Parametric Identification ◽  
Agricultural Crop ◽  
Parameter System ◽  
Plant Nitrogen ◽  
Rhizosphere Microorganisms ◽  
Nitrogen Phosphorus

A numerical simulation of the spatial-temporal dynamics of a multi-parameter system is developed. The components of this system are plant biomass, mobile and stationary forms of mineral nutrition elements, rhizosphere microorganisms and environmental parameters (temperature, humidity, acidity). Parametric identification and verification of the adequacy of the model were carried out based on the experimental data on the growth of spring wheat «Krasnoufimskaya-100» on peat lowland soil. The results are represented by temporal distributions of biomass from agricultural crop under study and the findings on the content of main nutrition elements within the plant (nitrogen, phosphorus, potassium). An agronomic assessment and interpretation of the obtained results are given.

scholarly journals Simultaneous Parameters Identifiability and Estimation of anE. coliMetabolic Network Model

2015 ◽  
Vol 2015 ◽  
pp. 1-21 ◽  
Author(s):  
Kese Pontes Freitas Alberton ◽  
André Luís Alberton ◽  
Jimena Andrea Di Maggio ◽  
Vanina Gisela Estrada ◽  
María Soledad Díaz ◽  
...  
Keyword(s):  
Experimental Data ◽  
Escherichia Coli ◽  
Metabolic Networks ◽  
Initial Conditions ◽  
Model Fit ◽  
Real Problem ◽  
Kinetic Rates ◽  
K 12 ◽  
Procedure Model

This work proposes a procedure for simultaneous parameters identifiability and estimation in metabolic networks in order to overcome difficulties associated with lack of experimental data and large number of parameters, a common scenario in the modeling of such systems. As case study, the complex real problem of parameters identifiability of theEscherichia coliK-12 W3110 dynamic model was investigated, composed by 18 differential ordinary equations and 35 kinetic rates, containing 125 parameters. With the procedure, model fit was improved for most of the measured metabolites, achieving 58 parameters estimated, including 5 unknown initial conditions. The results indicate that simultaneous parameters identifiability and estimation approach in metabolic networks is appealing, since model fit to the most of measured metabolites was possible even when important measures of intracellular metabolites and good initial estimates of parameters are not available.

Numerical Simulation of Instantaneous Flashing LPG Release

2011 ◽  
Vol 236-238 ◽  
pp. 2660-2663
Author(s):  
Xiao Liu ◽  
Wei Tan ◽  
Yu Bu ◽  
Yu Jin Liu ◽  
Ze Jun Wang
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Initial Conditions ◽  
Expansion Process ◽  
Two Phase ◽  
Open Environment ◽  
Mass And Heat Transfer ◽  
Rate Of Evaporation ◽  
Instantaneous Release ◽  
Dynamics Method

An accident instantaneous release of LPG can results in a rapidly expanding two-phase flammable cloud, which is the medium of potentially disastrous consequences. In this paper, CFD (Computational Fluid Dynamics) method was applied for instantaneous LPG release in an open environment in order to analysis the expansion process of two-phase cloud. The results from simulation are compared with the published experimental data to validate the model. Statistical analysis of experimental data is used to set the initial conditions and computational inlet in the model. The mass and heat transfer is calculated in eulerian-lagrangian method. The features in expansion process are studied by the analyses of the variation of size, temperature, volume averaged rate of evaporation of the cloud and entropy of the whole flow field.

scholarly journals Heuristic study of a full can implementation on a network of digital controllers based on experimental data

2020 ◽  
pp. 17-23
Author(s):  
Carlos Alberto Luján-Ramírez ◽  
Jesús Sandoval-Gío ◽  
Agustín Alfonso Flores-Novelo ◽  
Juan Alberto Ojeda-Arana
Keyword(s):  
Experimental Data ◽  
Parametric Identification ◽  
Operating Conditions ◽  
Access Time ◽  
Area Network ◽  
Digital Controllers ◽  
Electromagnetic Brake ◽  
Control Loops ◽  
Heuristic Study ◽  
Exchange Data

Over time, the CAN (Controller Area Network) communication bus has been implemented in different technological sectors, within which, depending on the application, the bus implementation may change. On the other hand, the design and implementation of digital controls based on experimental data is a well-known topic in the automation industry where the acquisition system is of great importance. In this document, a heuristic study of the behavior of a Full CAN network is reported to implement digital controllers in two interconnected control loops. This study takes into account the access time to the bus and the amount of data sent when observing the response to disturbances. The design of two digital controllers is presented based on the parametric identification of two plants: a DC motor with an electromagnetic brake and a pneumatic levitator. Using PSoC® microcontrollers, a Full CAN network is implemented, where the digital controllers exchange data by randomly accessing the bus. A specially designed interface allows visualizing the speed and amount of data transferred under different operating conditions of the control loops. At the document end, the experimental data obtained are discussed.

scholarly journals Interpolation of Boundary Condition at Time-Interval of Unknown Lenghth for the Problem of Convective Diffusion in a Three-Layered Water Filter

2019 ◽  
pp. 25-28
Author(s):  
Olha Chernukha ◽  
Yurii Bilushchak
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Mass Transfer ◽  
Boundary Condition ◽  
Boundary Value Problem ◽  
Convective Diffusion ◽  
Lower Boundary ◽  
Time Interval ◽  
Water Filter ◽  
The Right

On the basis of mathematical model of convectivediffusion in a three-layered filter it is formulated a contactinitial-boundary value problem for description of mass transferof pollution accompanying the sorption processes. It is proposedthe algorithm for establishing the estimation of values of soughtfunction (concentration of pollution) at the lower boundary of thefilter on the basis of the interpolation of experimental data. It istaken into account that the right end of the interpolation segmentis unknown. It is determined the exact solutions of contact-initialboundaryvalue problems of mass transfer with provision forboth diffusive and convective mechanisms of transfer as well assorption processes, which is based on integral transformationsover space variables in the contacting regions. Is it designedsoftware and established regularities of convective diffusionprocess in the three-layered filter.

A Variational Approach To The Optimization of Gait For a Bipedal Robot

1996 ◽  
Vol 210 (2) ◽  
pp. 177-186 ◽  
Author(s):  
P H Channon ◽  
S H Hopkins ◽  
D T Pham
Keyword(s):  
Finite Difference ◽  
Variational Approach ◽  
Dynamic Models ◽  
Initial Conditions ◽  
Optimal Trajectories ◽  
Point Boundary ◽  
Variational Technique ◽  
Bipedal Robot ◽  
Finite Difference Technique ◽  
Linearized Model

This paper presents a method for optimizing the walking motions of a planar five-link biped. The technique starts with non-linear kinematic and dynamic models for both the single-support and impact stages of motion. A variational technique is then used to derive joint trajectories that minimize a simple cost function. The resulting two-point boundary value problem is solved using a finite difference technique, with trajectories obtained from a simple linearized model as initial conditions. Families of optimal trajectories for different step periods and step lengths are presented.

Efficient dynamic analysis of a whole aeroengine using identified nonlinear bearing models

2011 ◽  
Vol 226 (1) ◽  
pp. 66-81 ◽  
Author(s):  
K H Groves ◽  
P Bonello ◽  
P M Hai
Keyword(s):  
Dynamic Performance ◽  
Computational Cost ◽  
Parametric Identification ◽  
Frequency Domain Analysis ◽  
Reduced Form ◽  
Squeeze Film ◽  
Computational Time ◽  
Parameter Study ◽  
Accurate Identification ◽  
Non Linear

Essential to effective aeroengine design is the rapid simulation of the dynamic performance of a variety of engine and non-linear squeeze-film damper (SFD) bearing configurations. Using recently introduced non-linear solvers combined with non-parametric identification of high-accuracy bearing models it is possible to run full-engine rotordynamic simulations, in both the time and frequency domains, at a fraction of the previous computational cost. Using a novel reduced form of Chebyshev polynomial fits, efficient and accurate identification of the numerical solution to the two-dimensional Reynolds equation (RE) is achieved. The engine analysed is a twin-spool five-SFD engine model provided by a leading manufacturer. Whole-engine simulations obtained using Chebyshev-identified bearing models of the finite difference (FD) solution to the RE are compared with those obtained from the original FD bearing models. For both time and frequency domain analysis, the Chebyshev-identified bearing models are shown to mimic accurately and consistently the simulations obtained from the FD models in under 10 per cent of the computational time. An illustrative parameter study is performed to demonstrate the unparalleled capabilities of the combination of recently developed and novel techniques utilised in this paper.

Sign in / Sign up

Export Citation Format

Share Document