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Adaptation Rate (adaptation + rate)

Distribution by Scientific Domains
Engineering75%

Selected Abstracts

Predictive adaptive control of plants with online structural changes based on multiple models

INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 8 2008
J. M. Lourenço
Abstract The objective of this paper is to present a new algorithm to improve the adaptation rate of a predictive adaptive controller. For that sake, the possible plant dynamic outcomes are covered by a bank of models. Each model is used to re-initialize the adaptive controller every time there is a large change in dynamics. The contribution of the paper consists in the development of a procedure that includes additional models in the bank when found suitable according to defined criteria. The algorithm is demonstrated in a benchmark problem consisting of the position control of two masses coupled by a spring of varying stiffness. Copyright © 2008 John Wiley & Sons, Ltd. [source]

A rapidly converging filtered-error algorithm for multichannel active noise control

INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 7 2007
A. P. Berkhoff
Abstract In this paper, a multichannel adaptive control algorithm is described which has good convergence properties while having relatively small computational complexity. This complexity is similar to that of the filtered-error algorithm. In order to obtain these properties, the algorithm is based on a preprocessing step for the actuator signals using a stable and causal inverse of the minimum-phase part of the transfer path between actuators and error sensors, the secondary path. The latter algorithm is known from the literature as postconditioned filtered-error algorithm, which improves convergence rate for the case that the minimum-phase part of the secondary path increases the eigenvalue spread. However, the convergence rate of this algorithm suffers from delays in the adaptation path because adaptation rates have to be reduced for larger delays. The contribution of this paper is to modify the postconditioned filtered-error scheme in such a way that the adaptation rate can be set to a higher value. Consequently, the scheme also provides good convergence if the system contains significant delays. Furthermore, a regularized extension of the scheme is given which can be used to limit the actuator signals. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Analytical approach to the optimal adaptation rate of reconfigurable radio networks

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 7 2008
R. Fraile
Abstract Flexible radio resource management schemes are nowadays used within a wide range of systems. However, the optimal selection for their adaptation rate is still an open research issue. This paper presents an analytical approach to such problem, which consists in a combined analysis of the dynamics of the session-arrival process and the estimation of the mean traffic load from network measurements. From this study, it is concluded that both aspects pose an upper limit on the optimal system adaptation rate, being the most restrictive the one depending on the mean traffic load estimation. A specific procedure for deriving such limit on adaptation rate is provided. It is shown that the derived value directly depends on the mean service duration. The application of the whole analysis is illustrated with an example based on a set of measurements from a live network. Copyright © 2008 John Wiley & Sons, Ltd. [source]

A rapidly converging filtered-error algorithm for multichannel active noise control

INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 7 2007
A. P. Berkhoff
Abstract In this paper, a multichannel adaptive control algorithm is described which has good convergence properties while having relatively small computational complexity. This complexity is similar to that of the filtered-error algorithm. In order to obtain these properties, the algorithm is based on a preprocessing step for the actuator signals using a stable and causal inverse of the minimum-phase part of the transfer path between actuators and error sensors, the secondary path. The latter algorithm is known from the literature as postconditioned filtered-error algorithm, which improves convergence rate for the case that the minimum-phase part of the secondary path increases the eigenvalue spread. However, the convergence rate of this algorithm suffers from delays in the adaptation path because adaptation rates have to be reduced for larger delays. The contribution of this paper is to modify the postconditioned filtered-error scheme in such a way that the adaptation rate can be set to a higher value. Consequently, the scheme also provides good convergence if the system contains significant delays. Furthermore, a regularized extension of the scheme is given which can be used to limit the actuator signals. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Efficiency of naphthalene biodegradation by Pseudomonas putida G7 in soil

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2004
Andrei E Filonov
Abstract The efficiency of naphthalene degradation by Pseudomonas putida G7 in soil was assessed using a mathematical model. The number of microorganisms and the concentration of naphthalene in soil samples were monitored. The feasibility of a spectrofluorometric method for naphthalene assay in soil samples was compared with high pressure liquid chromatography. A proposed mathematical model described the growth of the naphthalene-degrading strains and the consumption of substrates (naphthalene, naphthalene degradation intermediates and soil organic substances) in soil. To describe the growth kinetics of microorganisms having high affinity to substrates with low solubility, two differential equations with substrate exponent 2/3 were proposed. These equations were used to describe utilization of soil organic matter. The model parameters characterize the growth rates for different substrates and respective yield coefficients, specific bacterial death and adaptation rates, and also the rates of PAHs degradation and evaporation. These characteristics can be used in choosing the bacterial strains for biopreparations and efficient clean-up biotechnology of polluted soils. Copyright © 2004 Society of Chemical Industry [source]

Quantification of dark adaptation dynamics in retinitis pigmentosa using non-linear regression analysis

CLINICAL AND EXPERIMENTAL OPTOMETRY, Issue 6 2004
Rokiah Omar PhD
Purpose: Non-linear regression analysis was used to determine dark adaptation indices in people with retinitis pigmentosa and in control subjects. Methods: Dark adaptation data were collected for 13 people with retinitis pigmentosa and 21 controls using the Goldmann-Weekers Dark Adaptometer. Data were analysed using an exponential non-linear regression model and dark adaptation indices derived. The results were compared to age-related values. Results: The mean cone threshold of the group with RP (4.73 ± 0.19 log units) was significantly greater than that found in the control group (3.69 ± 0.12 log units). The rate of cone dark adaptation in the RP group was not significantly different from that of the control group. The a break in the RP group (6.46 ± 0.70 minutes) was delayed when compared to the control group (4.29 ± 0.21 minutes) and the rate of rod dark adaptation in the RF' group was slower (10 ± 2 per cent per minute) than that of the control group (15 ± 1 per cent per minute). Conclusions: This study has shown that a relatively simple data analysis can provide a more quantitative and intuitive description of dark adaptation rates in people with retinal disease. This technique will enable more effective use of dark adaptometry as a supplement to objective electrophysiology, when monitoring people with retinitis pigmentosa. [source]