Modèles en iles pour le réglage automatique de paramètres : application au problème du bandit manchot

National audienc

Parameter Setting with Dynamic Island Models

In this paper we proposed the use of a dynamic island model which aim at adapting parameter settings dynamically. Since each island corresponds to a specific parameter setting, measuring the evolution of islands populations sheds light on the optimal parameter settings efficiency throughout the search. This model can be viewed as an alternative adaptive operator selection technique for classic steady state genetic algorithms. Empirical studies provide competitive results with respect to other methods like automatic tuning tools. Moreover, this model could ease the parallelization of evolutionary algorithms and can be used in a synchronous or asynchronous way

Pourquoi rendre les modèles en iles autonomes ?

Date du colloque : 04/2012National audienc

Non stationary operator selection with island models

The purpose of adaptive operator selection is to choose dynamically the most suitable variation operator of an evolutionary algorithm at each iteration of the search process. These variation operators are applied on individuals of a population which evolves, according to an evolutionary process, in order to find an optimal solution. Of course the efficiency of an operator may change during the search and therefore its application should be precisely controlled. In this paper, we use dynamic island models as operator selection mechanisms. A sub-population is associated to each operators and individuals are allowed to migrate from one sub-population to another one. In order to evaluate the performance of this adaptive selection mechanism, we propose an abstract operator representation using fitness improvement distributions that allow us to define non stationary operators with mutual interactions. Our purpose is to show that the adaptive selection is able to identify not only good operators but also suitable sequences of operators

Chromosome numbers of two Colchicum L. species, C. burttii and C. balansae, from Turkey

No Abstrac

A dynamic island model for adaptive operator selection

In this paper we propose a generic framework for Dynamic Island Models, which can be used as an original approach for the adaptive selection of operators in evolutionary algorithms. Assigning a variation operator to each island, we show that the dynamic regulation of migrations, which takes into account the pertinence of recent migrations, distributes the individuals on the most promising islands, i.e., the most efficient operators, at each stage of the search. The efficiency of this approach is assessed on the One-Max problem by comparing theoretical expected results to those obtained by our dynamic island model. Experiments show that the model provides the expected behavior

Diagnostic value of combined serum biomarkers for the evaluation of liver fibrosis in chronic hepatitis C infection: A multicenter, noninterventional, observational study

Background/Aims: The hepatitis C virus (HCV) infection is important cause of chronic hepatitis. Liver biopsy is considered the gold standard for assessment of fibrosis but this procedure is an invasive procedure. We aimed to evaluate the diagnostic efficiency of non-invasive serum biomarkers, separately and in combinations, on liver fibrosis in treatment-naive chronic hepatitis C (CHC) patients. Materials and Methods: Two hundred and sixteen treatment-naive CHC patients were enrolled from 32 locations across Turkey in this open-labelled, non-interventional prospective observational study. FibroTest®, aspartate aminotransferase-to-platelet ratio index(APRI), aspartate aminotransferase and alanine aminotransferase ratio (AAR), fibrosis index based on four factors (FIB-4), Age-platelet(AP) index and Forns index were measured and compared with Metavir scores got from liver biopsies. Results: Data from 182 patients with baseline liver biopsy were suitable for analysis. One hundred and twenty patients (65.9%) had F0-F1 fibrosis and 62 patients (34.1%) had F2-F4 fibrosis. APRI 0.732 area under the curve(AUC) indicated advanced fibrosis with 69% sensitivity and 77% specificity. FIB-4 0.732 AUC and FibroTest 0.715 AUC indicated advanced fibrosis with 69% and 78.4% sensitivity, and 75% and 71.4% specificity, respectively. The combined use of tests also led to an increase in AUC and specificity. Combinations of FibroTest with APRI and/or FIB-4, and FIB-4 with APRI were optimal for the evaluation of liver fibrosis. Conclusion: Fibrotest, FIB-4, APRI, AP index and Forns index exhibit good diagnostic performance for determining liver fibrosis in CHC patients, and the use of at least two tests together will increase their diagnostic value still further. © Copyright 2018 by The Turkish Society of Gastroenterology

Real-time interval type-2 fuzzy control of an unmanned aerial vehicle with flexible cable-connected payload

This study presents the design and real-time applications of an Interval Type-2 Fuzzy PID (IT2-FPID) control system on an unmanned aerial vehicle (UAV) with a flexible cable-connected payload in comparison to the PID and Type-1 Fuzzy PID (T1-FPID) counterparts. The IT2-FPID control has significant stability, disturbance rejection, and response time advantages. To prove and show these advantages, the DJI Tello, a commercial UAV, is used with a flexible cable-connected payload to test the robustness of PID, T1-FPID, and IT2-FPID controllers. First, the optimal coefficients of the compared controllers are found using the Big Bang–Big Crunch algorithm via the nonlinear UAV model without the payload. Second, once optimised, the controllers are tested using several scenarios, including disturbing the payload and the coverage path planning area to examine their robustness. Third, the controller performance results are evaluated according to reference achievement and point-based tracking under disturbances. Finally, the superiority of the IT2-FPID controller is shown via simulations and real-time experiments with a better overshoot, a faster settling time, and good properties of disturbance rejection compared with the PID and the T1-FPID controllers

Craniofacial Evaluation of Class I Turkish Adults: Bimler Analysis

Objective:The aim of this study was to evaluate the facial type and skeletal relationships of Class I Turkish male and female adults by using Bimler cephalometric analysis.Materials and Method:The study sample included 82 randomly selected Turkish adults (42 female, 40 male) with an age range of 18–23 years. Cephalometric measurements defined by Bimler were used to determine skeletal relationships, including his suborbital facial index on lateral cephalometric radiographs. Variance analysis (ANOVA) was used for statistical assessment of the results.Results:The whole sample was found to be in the medium range according to Bimler. For all parameters, except the mandibular flexion (Cgo/CV), which showed hyperflexion with a mean 4.23° in female patients and 3.78° in male patients, Turkish adults show appropriate characteristics as defined by Bimler. There were no significant differences between men and women in most of the angular and linear measurements. Craniofacial height and depth values were significantly higher in men, showing a sex-based difference (p<0.001), whereas differences between the sexes concerning suborbital facial index (H/D) were nonsignificant.Conclusions:Ranges of Turkish population show similarity to those reported by Bimler. The whole sample was found to be in the medium range according to Bimler. Craniofacial height and depth values were significantly higher in men, showing sex-based difference. The mandible showed hyperflexion in both groups which indicates reduction of the height of the middle part of the face

Migratory corridors and foraging hotspots: Critical habitats identified for Mediterranean green turtles

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordAim: Levels of sea turtle bycatch in the Mediterranean are thought to be unsustainable. We provide a comprehensive overview of adult green turtle (Chelonia mydas) distribution during nesting, migration and foraging phases, highlighting transitory as well as residential areas of high use to facilitate adequate protection for this long-lived, migratory species. Location: Mediterranean Sea. Methods: Thirty-four females were satellite tracked from breeding grounds in the four countries with major nesting (Cyprus, Turkey, Israel and Syria) for a total of 8521 (mean: 251) tracking days in a collaborative effort to summarize the most comprehensive set of distribution data thus far assembled for this species in the Mediterranean. Results: Ten foraging grounds are identified, with two major hotspots in Libya accounting for >50% of turtles tracked to conclusive endpoints. The coastlines of Egypt and Libya contain high densities of migrating turtles following the nesting season, particularly July-September, and likely also pre-nesting (April-June). A high-use seasonal pelagic corridor running south-west from Turkey and Cyprus to Egypt is also evident, used by >50% of all tracked turtles. Main conclusions: Bycatch levels and mortality rates for the key foraging areas and high-density seasonal pathways identified here are largely unknown and should be investigated as a priority. We recommend that the Gulf of Sirte in Libya be explored as a potential biodiversity hotspot and considered for proposal as a marine protected area (MPA). Green turtle fidelity to nesting beaches, foraging areas and migratory pathways renders them vulnerable to localized threats but enables targeted mitigation measures and protection