Search results for "Adaptive"
showing 10 items of 792 documents
Adaptive control of a seven mode truncation of the Kolmogorov flow with drag
2009
Abstract We study a seven dimensional nonlinear dynamical system obtained by a truncation of the Navier–Stokes equations for a two dimensional incompressible fluid with the addition of a linear term modelling the drag friction. We show the bifurcation sequence leading from laminar steady states to chaotic solutions with increasing Reynolds number. Finally, we design an adaptive control which drives the state of the system to the equilibrium point representing the stationary solution.
On the accuracy of the fast hierarchical DBEM for the analysis of static and dynamic crack problems
2010
In this paper the main features of a fast dual boundary element method based on the use of hierarchical matrices and iterative solvers are described and its effectiveness for fracture mechanics problems, both in the static and dynamic case, is demonstrated. The fast solver is built by representing the collocation matrix in hierarchical format and by using a preconditioned GMRES for the solution of the algebraic system. The preconditioner is computed in hierarchical format by LU decomposition of a coarse hierarchical representation of the collocation matrix. The method is applied to elastostatic problems and to elastodynamic cases represented in the Laplace transform domain. The application …
Adaptive high-gain extended kalman filter and applications
2010
The work concerns the ``observability problem” --- the reconstruction of a dynamic process's full state from a partially measured state--- for nonlinear dynamic systems. The Extended Kalman Filter (EKF) is a widely-used observer for such nonlinear systems. However it suffers from a lack of theoretical justifications and displays poor performance when the estimated state is far from the real state, e.g. due to large perturbations, a poor initial state estimate, etc… We propose a solution to these problems, the Adaptive High-Gain (EKF). Observability theory reveals the existence of special representations characterizing nonlinear systems having the observability property. Such representations…
Mobile Encounter Network - the missing data link
2008
In this paper, we discuss about the applicability of a short-range wireless communication scheme called Mobile Encounter Network (MEN). Encounters between devices communicating while moving allows ad-hoc -type data transfer to be performed. A background for the emerging of such networks is given. The essential properties of the MEN data transfer are specified. Based on this, the role of MEN as a data transfer medium is discussed. The conclusion is that such networking technique may provide additional value compared to the traditional wireless communication.
Optimal extension of multispectral image demosaicking algorithms for setting up a one-shot camera video acquisition system
2022
Multispectral images are acquired using multispectral cameras equipped with CCD or CMOS sensors which sample the visible or near infrared spectrum according to specific spectral bands. A mosaic of multispectral MSFA filters is superimposed on the surface of the sensors to acquire a raw image called an MSFA image. In the MSFA image, only one spectral band is available per pixel, the demosaicking process is necessary to estimate the multispectral image at full spatio-spectral resolution. Motivated by the success of single-sensor cameras capturing the image in a single exposure that use CFA filters, we performed a comparative study of a few recent color image demosaicking algorithms and experi…
To transmit genes without becoming mother: An evolutionary conflict behind denial of pregnancy
2016
Aim: The etiology of pregnancy denial remains poorly understood. Neither necessary nor sufficient conditions can be synthesized from the risk factors identified from psychological analyses. In accordance with clinical observations, we aim to explain denial of pregnancy from an evolutionary conflict perspective. Methods: Authors investigate evolutionary biology aspects and emphasize on the transition from solitary animal species to social species. The possibility of conflicts between primitive species-perpetuation forces and subjective social-identity forces are explored. Results: As members of a social species, human beings have a dual, contradictory character of independent organisms but i…
Liver fibrosis: Common mechanisms and antifibrotic therapies
2015
Liver fibrosis and in particular cirrhosis have become major endpoints in clinical trials of patients with chronic liver diseases. Here, viral hepatitis, alcoholic and non-alcoholic steatohepatitis have become the major etiologies. We have made great progress in our understanding of the mechanisms and the cell biology of liver fibrosis and have already made the transition from preclinical testing of antifibrotic agents and strategies towards clinical translation. There continues to be an urgent need for specific antifibrotic therapies, despite the advent of highly potent antiviral agents that can even induce regression of advanced fibrosis. This review addresses central mechanisms and cells…
Branch and bound for the cutwidth minimization problem
2013
The cutwidth minimization problem consists of finding a linear arrangement of the vertices of a graph where the maximum number of cuts between the edges of the graph and a line separating consecutive vertices is minimized. We first review previous approaches for special classes of graphs, followed by lower bounds and then a linear integer formulation for the general problem. We then propose a branch-and-bound algorithm based on different lower bounds on the cutwidth of partial solutions. Additionally, we introduce a Greedy Randomized Adaptive Search Procedure (GRASP) heuristic to obtain good initial solutions. The combination of the branch-and-bound and GRASP methods results in optimal solu…
The Function of Plastic Reproductive Behaviour in Drosophila melanogaster
2022
Phenotypic plasticity is a widespread phenomenon across the tree of life, with far reaching consequences for ecological and evolutionary processes. In species facing strong sexual selection and marked variation in the socio-sexual context in which they reproduce, adaptive plasticity in reproductive behaviour is expected to evolve. In this thesis, we aimed to contribute to this area of evolutionary biology research using the model organism Drosophila melanogaster. The results of this thesis offer a twist to the steadily growing literature of ageing via sensory perception by showing that socio-sexual cues so far documented to accelerate ageing mostly bear fitness benefits in ecologically rele…
E-heutagogy for lifelong e-learning
2012
Abstract The paper aims to introduce a new concept: e-heutagogy. This aim is approached through two sub-objectives:a) Giving the rationale for the new concept of e-heutagogy.b) Outlining the features of e-heutagogy necessary for lifelong e-learning.Why do we need a new concept? Learning is a complex concept and it is a part of our entire life. Today we can speak about new generations of learners at all levels, from kindergarten to university, not only due to technology but also due to rapid changes in open, heterogeneous, dynamic and uncertain environments.Taking into account that heutagogy is appropriate to the needs of learners but learners are most of their life without their teachers an…