Modeling and Design Implications of Noncollocated Control in Flexible Systems

1990 ◽  
Vol 112 (2) ◽  
pp. 186-193 ◽  
Author(s):  
V. A. Spector ◽  
H. Flashner
Keyword(s):  
Transfer Function ◽  
Structural Control ◽  
High Sensitivity ◽  
Wave Number ◽  
Model Parameters ◽  
Generic Properties ◽  
Distributed Sensors ◽  
Function Zeros ◽  
Euler Bernoulli Beam ◽  
Qualitative Characteristics

In this paper we investigate generic properties of structural modeling pertinent to structural control, with emphasis on noncollocated systems. Analysis is performed on a representative example of a pinned-free Euler-Bernoulli beam with distributed sensors. Analysis in the wave number plane highlights the crucial qualitative characteristics common to all structural systems. High sensitivity of the transfer function zeros to errors in model parameters and sensor locations is demonstrated. The existence of finite right half plane zeros in noncollocated systems, along with this high sensitivity, further complicates noncollocated controls design. A numerical method for accurate computation of the transfer function zeros is proposed. Wiener-Hopf factorization is used to compute equivalent delay time, which is important in controls design.

Physical Properties of Transfer Function Zeros for Collocated Control in Flexible Structure System

1995 ◽  
Author(s):  
Chingyei Chung ◽  
Chin-yuh Lin
Keyword(s):  
Transfer Function ◽  
Circulatory System ◽  
Flexible Structure ◽  
Structure System ◽  
Zero Dynamic ◽  
Damping Matrix ◽  
Generalized Force ◽  
Function Zeros ◽  
Gyroscopic Systems ◽  
Collocated Control

Abstract In this paper, the physical meaning of transfer function zeros for collocated control in a general flexible structure system is discussed. For a flexible structure system, we propose the “Zero Dynamic Theorem”. The theorem states that in a flexible structure system, the flexible structure can be a circulatory system (non-sysmetric stiffness matrix) with viscous and gyroscopic damping (non-symmetric damping matrix), if the sensor output (generalized displacement) and the actuator input (generalized force) are “dual type” and the transfer function is strict proper and coprime (no pole/zero cancellation); then, the transfer function zeros are the natural frequencies of constrained structure. Furthermore, with this theorem, the interlacing pole/zero property for the gyroscopic systems is presented.

scholarly journals Parameter Estimation of DC Motor using Adaptive Transfer Function Based on Nelder-Mead Optimisation

2018 ◽  
Vol 9 (3) ◽  
pp. 696 ◽  
Author(s):  
Byamakesh Nayak ◽  
Sangeeta Sahu ◽  
Tanmoy Roy Choudhury
Keyword(s):  
Experimental Data ◽  
Transfer Function ◽  
Adaptive Method ◽  
Dc Motor ◽  
Model Parameters ◽  
Current Response ◽  
Adaptive Model ◽  
Unknown Parameters ◽  
Dc Motors ◽  
Estimated Parameters

<p>This paper explains an adaptive method for estimation of unknown parameters of transfer function model of any system for finding the parameters. The transfer function of the model with unknown model parameters is considered as the adaptive model whose values are adapted with the experimental data. The minimization of error between the experimental data and the output of the adaptive model have been realised by choosing objective function based on different error criterions. Nelder-Mead optimisation Method is used for adaption algorithm. To prove the method robustness and for students learning, the simple system of separately excited dc motor is considered in this paper. The experimental data of speed response and corresponding current response are taken and transfer function parameters of  dc motors are adapted based on Nelder-Mead optimisation to match with the experimental data. The effectiveness of estimated parameters with different objective functions are compared and validated with machine specification parameters.</p>

Prediction and suppression of long-period nonpropagating seismic noise

1973 ◽  
Vol 63 (3) ◽  
pp. 937-958
Author(s):  
Anton Ziolkowski
Keyword(s):  
Transfer Function ◽  
Pressure Distribution ◽  
Noise Level ◽  
Seismic Noise ◽  
Wave Number ◽  
Earth Model ◽  
Noise Power ◽  
Long Period ◽  
Band Limited ◽  
Time Invariant

abstract Approximately half the noise observed by long-period seismometers at LASA is nonpropagating; that is, it is incoherent over distances greater than a few kilometers. However, because it is often strongly coherent with microbarograph data recorded at the same site, a large proportion of it can be predicted by convolving the microbarogram with some transfer function. The reduction in noise level using this technique can be as high as 5 db on the vertical seismometer and higher still on the horizontals. If the source of this noise on the vertical seismogram were predominantly buoyancy, the transfer function would be time-invariant. It is not. Buoyancy on the LASA long-period instruments is quite negligible. The noise is caused by atmospheric deformation of the ground and, since so much of it can be predicted from the output of a single nearby microbarograph, it must be of very local origin. The loading process may be adequately described by the static deformation of a flat-earth model; however, for the expectation of the noise to be finite, it is shown that the wave number spectrum of the pressure distribution must be band-limited. An expression for the expected noise power is derived which agrees very well with observations and predicts the correct attenuation with depth. It is apparent from the form of this expression why it is impossible to obtain a stable transfer function to predict the noise without an array of microbarographs and excessive data processing. The most effective way to suppress this kind of noise is to bury the seismometer: at 150 m the reduction in noise level would be about 10 db.

scholarly journals Gravity wave propagation in the realistic atmosphere based on a three-dimensional transfer function model

2007 ◽  
Vol 25 (9) ◽  
pp. 1979-1986 ◽  
Author(s):  
L. Sun ◽  
W. Wan ◽  
F. Ding ◽  
T. Mao
Keyword(s):  
Transfer Function ◽  
Gravity Wave ◽  
Gravity Waves ◽  
Minimum Energy ◽  
Three Dimensional ◽  
Wave Number ◽  
Transfer Function Model ◽  
Wave Band ◽  
Function Model ◽  
Ionospheric Height

Abstract. In order to study the filter effect of the background winds on the propagation of gravity waves, a three-dimensional transfer function model is developed on the basis of the complex dispersion relation of internal gravity waves in a stratified dissipative atmosphere with background winds. Our model has successfully represented the main results of the ray tracing method, e.g. the trend of the gravity waves to travel in the anti-windward direction. Furthermore, some interesting characteristics are manifest as follows: (1) The method provides the distribution characteristic of whole wave fields which propagate in the way of the distorted concentric circles at the same altitude under the control of the winds. (2) Through analyzing the frequency and wave number response curve of the transfer function, we find that the gravity waves in a wave band of about 15–30 min periods and of about 200–400 km horizontal wave lengths are most likely to propagate to the 300-km ionospheric height. Furthermore, there is an obvious frequency deviation for gravity waves propagating with winds in the frequency domain. The maximum power of the transfer function with background winds is smaller than that without background winds. (3) The atmospheric winds may act as a directional filter that will permit gravity wave packets propagating against the winds to reach the ionospheric height with minimum energy loss.

Individualized Transfer Functions for the Noninvasive Estimation of Central Pressure From Brachial Pressure Readings

2009 ◽  
Author(s):  
Ashis Mookerjee ◽  
Ahmed M. Al-Jumaily ◽  
Andrew Lowe
Keyword(s):  
Blood Pressure ◽  
Transfer Function ◽  
Brachial Artery ◽  
Transfer Functions ◽  
Patient Characteristics ◽  
Patient Specific ◽  
Model Parameters ◽  
Brachial Blood Pressure ◽  
Noninvasive Estimation ◽  
Artery Segment

A model-based investigation is carried out with the aim of developing an ab-initio methodology for the patient-specific estimation of central pressures from brachial blood pressure readings. The subclavian root-brachial artery segment is modeled as a 1-D tube with all model parameters linked to patient characteristics. A simulation is also run with typical physiological parameters, which gives a “first estimate” of the transfer function (TF). The TF derived using the patient characteristics is studied in detail to investigate the change in the arterial TF occurring with changes in patient characteristics. This TF is compared with the “first estimate” to evaluate the feasibility of using standard arterial properties.

scholarly journals First millimeter Mapping of the jet and nucleus of M87

1996 ◽  
Vol 175 ◽  
pp. 175-176
Author(s):  
V. Despringre ◽  
D. Fraix-Burnet
Keyword(s):  
Thermal Emission ◽  
Cutoff Frequency ◽  
Low Frequency ◽  
High Sensitivity ◽  
Model Parameters ◽  
Relativistic Electrons ◽  
Extragalactic Jets ◽  
Molecular Lines ◽  
Optical Wavelengths ◽  
Cold Dust

An intriguing question about extragalactic jets is why they are so few being seen at optical wavelengths, or equivalently, why the cutoff frequency of the synchrotron radiation is generally not in the optical, but rather in the infrared or even in the sub- millimeter domain. The answer is undoubtedly related to the efficiency of the acceleration of the relativistic electrons responsible for the synchrotron emission. The presence of a break at low frequency somewhere in the synchrotron spectrum is another feature that constrains the model parameters, but its precise location is unknown for most jets, because of the lack of photometry in the millimeter domain. It was thus necessary to fill the gap between radio and optical wavelengths in the synchrotron spectrum of optical jets. The required observation had to be of high sensitivity and high spatial resolution (of the order of 1″). Another reason for observing at millimeter wavelengths is that molecular lines and thermal emission from cold dust are detectable in this frequency range.

Physical Interpretation of Transfer Function Zeros for Simple Control Systems With Mechanical Flexibilities

1991 ◽  
Vol 113 (3) ◽  
pp. 419-424 ◽  
Author(s):  
D. K. Miu
Keyword(s):  
Transfer Function ◽  
Control Systems ◽  
Physical Interpretation ◽  
Complex Conjugate ◽  
Flexible Structure ◽  
Resonant Frequencies ◽  
Nonminimum Phase ◽  
Flexible Control ◽  
Real Zeros ◽  
Function Zeros

Physical interpretation of the transfer function zeros of simple control systems with mechanical flexibilities is presented. It is shown that for discrete spring-mass systems and elastic beams, the poles are the resonant frequencies of the flexible structure and the complex conjugate zeros are the resonant frequencies of a substructure constrained by the sensor and actuator. It is also shown that when the flexible control systems become nonminimum phase, the real zeros are the results of nonpropagation of energy within the substructure.

Evaluation of allergic response using dynamic thermography

2015 ◽  
Vol 23 (1) ◽  
Author(s):  
E. Rokita ◽  
T. Rok ◽  
G. Tatoń
Keyword(s):  
Allergic Reaction ◽  
Skin Prick Test ◽  
High Sensitivity ◽  
Allergic Response ◽  
Coefficient Of Determination ◽  
Model Parameters ◽  
Prick Test ◽  
Skin Reactivity ◽  
Heated Area ◽  
Spatio Temporal

AbstractSkin dynamic termography supplemented by a mathematical model is presented as an objective and sensitive indicator of the skin prick test result. Termographic measurements were performed simultaneously with routine skin prick tests. The IR images were acquired every 70 s up to 910 s after skin prick. In the model histamine is treated as the principal mediator of the allergic reaction. Histamine produces vasolidation and the engorged vessels are responsible for an increase in skin temperature. The model parameters were determined by fitting the analytical solutions to the spatio-temporal distributions of the differences between measured and baseline temperatures. The model reproduces experimental data very well (coefficient of determination = 0.805÷0.995). The method offers a set of parameters to describe separately skin allergic reaction and skin reactivity. The release of histamine after allergen injection is the best indicator of allergic response. The diagnostic parameter better correlates with the standard evaluation of a skin prick test (correlation coefficient = 0.98) than the result of the thermographic planimetric method based on temperature and heated area determination (0.81). The high sensitivity of the method allows for determination of the allergic response in patients with the reduced skin reactivity.

Sign in / Sign up

Export Citation Format

Share Document