Search results for " adaptive"

Adaptive P-splines via L1-type penalty in generalized additive models

2022

A Seven Mode Truncation of the Kolmogorov Flow with Drag: Analysis and Control

2009

The transition from laminar to chaotic motions in a viscous °uid °ow is in- vestigated by analyzing a seven dimensional dynamical system obtained by a truncation of the Fourier modes for the Kolmogorov °ow with drag friction. An- alytical expressions of the Hopf bifurcation curves are obtained and a sequence of period doubling bifurcations are numerically observed as the Reynolds num- ber is increased for ¯xed values of the drag parameter. An adaptive stabilization of the system trajectories to an equilibrium point or to a periodic orbit is ob- tained through a model reference approach which makes the control global. Finally, the e®ectiveness of this control strategy is numerically illustra…

Enhanced Current Loop PI Controllers with Adaptive Feed-Forward Neural Network via Estimation of Grid Impedance: Application to Three-Phase Grid-Tied…

2022

This paper describes a single-stage grid-connected three-phase photovoltaic inverter feeding power to the grid. Using the Recursive Least Squares (RLS) Estimator, an online grid impedance technique is proposed in the stationary reference frame. The method iteratively estimates the grid resistance and inductance values and is effective in detecting inverter islanding according to IEEE standard 929-2000. An Adaptive Feedforward Neural (AFN) Controller has also been developed using the inverse of the system to improve the performance of the inner-loop Proportional-Integral controllers under dynamical conditions and provide better DC link voltage stability. The neural network weights are comput…

THE PROMOTION OF FUTURE PRIMARY SCHOOL TEACHERS’ ABILITY FOR ANALYSING COMPLEX EDUCATIONAL SITUATIONS. A METACOGNITIVE APPROACH

2013

When approaching and solving educational problems, those who are about to start a teaching profession, need to involve strategies in order to appropriately answer complex problems characterizing educational situations. We examine one way to promote specific transfer of general skills: a methodology entails the elicitation, analysis and inclusion of case-study as a primary form of instructional support while learning to solve problems. This approach is referred to as analysis of cases drawn from real-world educative contexts in order to help students develop problem solving skill. Learning is supported by conversations and stories about problematic and difficult cases. In this paper we intro…

Decentralization and heterogeneity in complex adaptative systems

2015

Purpose – Following a bacterial-based modeling approach, the authors want to model and analyze the impact of both decentralization and heterogeneity on group behavior and collective learning. The paper aims to discuss these issues. Design/methodology/approach – Inspired by bacterial conjugation, the authors have defined an artificial society in which agents’ strategies adapt to changes in resources location, allowing migration, and survival in a dynamic sugarscape-like scenario. To study the impact of these variables the authors have simulated a scenario in which resources are limited and localized. The authors also have defined three constraints in genetic information processing (inhibiti…

Holonic Handling the Unexpected in Project Management

2017

Abstract Risk assessment is one the key activities of any project. The unexpected situations can have catastrophic consequences. Risk assessment tries to estimate to potential known unknowns, but there is no guarantee to foresee all circumstances around a project. In this situation the project team must be adaptive and find solutions by cooperation, creativity and abductive reasoning. In the paper we tried to analyse on what extent a project and a project team can be handled as a complex adaptive system. More precisely, how the scientific and practical achievements of the theory of complex adaptive systems (CAS) can be used in project management. More exactly, we analyse the applicability o…

Detection and Recognition of Target Signals in Radar Clutter via Adaptive CFAR Tests

2006

In this paper, adaptive CFAR tests are described which allow one to classify radar clutter into one of several major categories, including bird, weather, and target classes. These tests do not require the arbitrary selection of priors as in the Bayesian classifier. The decision rule of the recognition techniques is in the form of associating the p-dimensional vector of observations on the object with one of the m specific classes. When there is the possibility that the object does not belong to any of the m classes, then this object is to be classified as belonging to one of the m classes or to class m+1 whose distribution is unspecified. The tests are invariant to intensity changes in the …

Generalization of Canny–Deriche filter for detection of noisy exponential edge

2002

This paper presents a generalization of the Canny-Deriche filter for ramp edge detection with optimization criteria used by Canny (signal-to-noise ratio, localization, and suppression of false responses). Using techniques similar to those developed by Deriche, we derive a filter which maximizes the product of the first two criteria under the constraint of the last one. The result is an infinite length impulse response filter which leads to a stable third-order recursive implementation. Its performance shows an increase of the signal-to-noise ratio in the case of blurred and noisy images, compared to the results obtained from Deriche's filter.

Sensorless Control of Induction-Motor Drive Based on Robust Kalman Filter and Adaptive Speed Estimation

2014

This paper deals with robust estimation of rotor flux and speed for sensorless control of motion control systems with an induction motor. Instead of using sixth-order extended Kalman filters (EKFs), rotor flux is estimated by means of a fourth-order descriptor-type robust KF, which explicitly takes into account motor parameter uncertainties, whereas the speed is estimated using a recursive least squares algorithm starting from the knowledge of the rotor flux itself. It is shown that the descriptor-type structure allows for a direct translation of parameter uncertainties into variations of the coefficients appearing in the model, and this improves the degree of robustness of the estimates. E…

Assisted Self-Adapted Testing: A Comparative Study

2004

Abstract: A new type of self-adapted test (S-AT), called Assisted Self-Adapted Test (AS-AT), is presented. It differs from an ordinary S-AT in that prior to selecting the difficulty category, the computer advises examinees on their best difficulty category choice, based on their previous performance. Three tests (computerized adaptive test, AS-AT, and S-AT) were compared regarding both their psychometric (precision and efficiency) and psychological (anxiety) characteristics. Tests were applied in an actual assessment situation, in which test scores determined 20% of term grades. A sample of 173 high school students participated. Neither differences in posttest anxiety nor ability were obta…