Search results for "Markov"

Fuzzy Distributed Genetic Approaches for Image Segmentation

2010

This paper presents a new image segmentation algorithm (called FDGA-Seg) based on a combination of fuzzy logic, multiagent systems and genetic algorithms. We propose to use a fuzzy representation of the image site labels by introducing some imprecision in the gray tones values. The distributivity of FDGA-Seg comes from the fact that it is designed around a MultiAgent System (MAS) working with two different architectures based on the master-slave and island models. A rich set of experimental segmentation results given by FDGA-Seg is discussed and compared to the ICM results in the last section.

Statistical Shape and Probability Prior Model for Automatic Prostate Segmentation

2011

International audience; Accurate prostate segmentation in Trans Rectal Ultra Sound (TRUS) images is an important step in different clinical applications. However, the development of computer aided automatic prostate segmentation in TRUS images is a challenging task due to low contrast, heterogeneous intensity distribution inside the prostate region, imaging artifacts like shadow, and speckle. Significant variations in prostate shape, size and contrast between the datasets pose further challenges to achieve an accurate segmentation. In this paper we propose to use graph cuts in a Bayesian framework for automatic initialization and propagate multiple mean parametric models derived from princi…

MRF Model-Based Approach for Image Segmentation Using a Chaotic MultiAgent System

2006

In this paper, we propose a new Chaotic MultiAgent System (CMAS) for image segmentation. This CMAS is a distributed system composed of a set of segmentation agents connected to a coordinator agent. Each segmentation agent performs Iterated Conditional Modes (ICM) starting from its own initial image created initially from the observed one by using a chaotic mapping. However, the coordinator agent receives and diversifies these images using a crossover and a chaotic mutation. A chaotic system is successfully used in order to benefit from the special chaotic characteristic features such as ergodic property, stochastic aspect and dependence on initialization. The efficiency of our approach is s…

Paredzošā stimulētā mācīšanās

2016

Continuous actor-critic learning automaton, jeb CACLA, algoritma aktiera un kritiķa komponentes ir apvienojamas vienā, izmantojot faktu, ka tās no stāvokļu telpas izgūst līdzīgas pazīmes savu funkciju veikšanai. Tas ļauj divas reizes samazināt to realizēšanā izmantotā neironu tīkla trenējamo parametru skaitu, kā arī ļauj aģentam ātrāk nonāk pie labas stratēģijas, jo optimālās stratēģijas funkcijas parametri tiek pielāgoti arī vērtību funkcijas izmaiņu rezultātā. Tas noved pie savdabīga optimālās stratēģijas funkcijas parametru nepārraudzītās mācīšanās procesa. Šāds netiešā veidā veikts optimālās stratēģijas funkcijas parametru pielāgošanas process atstāj ietekmi uz trenēšanas procesu, jo sa…

Memory ℋ<inf>∞</inf> control for continuous-time Markovian jump systems with time-varying delay and defective mode …

2014

Markovian approximation of linear systems with fractional viscoelastic term

2017

It is well known that the response of a linear system enforced by a Gaussian white noise is Markovian. The order of Markovianity is n-1 being n the maximum order of the derivative of the equation ruling the evolution of the system. However when a fractional operator appears, the order of Markovianity of the system becomes infinite. Then the main aim developed in the proposed paper, consists of rewriting the system with fractional term of order r with an "equivalent" one, in which the fractional operator is substituted by two classical differential terms with integer order of derivative int(r) and int(r + 1) (for a real r). In this way the fractional differential equation reverts into a clas…

Diferenciālvienādojumu ar Markova impulsu atgriezenisko saiti asimptotiskās analīzes robežteorēmas

1999

Matemātika

2005

A Quasi-likelihood Markov model for the hardenability of steel

1992

To evaluate the hardenability of steel the Jominy test can be used. A steel bar of fixed dimensions is heated up to about 850 °C and then quenched from one end by water spray. Its hardness y is then measured at increasing distances d from this quenched end giving observations (d, y(d)), which form the Jominy curve. For each Jominy curve these observations can be fitted by descending curve μ = μ(d; η) with shape parameters η = (η 1,..., η p ) T which are assumed to vary along the alloying elements (C, Mn, Cr etc.).

Communities of Local Optima as Funnels in Fitness Landscapes

2016

We conduct an analysis of local optima networks extracted from fitness landscapes of the Kauffman NK model under iterated local search. Applying the Markov Cluster Algorithm for community detection to the local optima networks, we find that the landscapes consist of multiple clusters. This result complements recent findings in the literature that landscapes often decompose into multiple funnels, which increases their difficulty for iterated local search. Our results suggest that the number of clusters as well as the size of the cluster in which the global optimum is located are correlated to the search difficulty of landscapes. We conclude that clusters found by community detection in local…