4 sonuçlar
Arama Sonuçları
Listeleniyor 1 - 4 / 4
Öğe A novel approach for extracting ideal exemplars by clustering for massive time-ordered datasets(TÜBİTAK, 2017-07-30) Ertuğrul, Ömer FarukThe number and length of massive datasets have increased day by day and this yields more complex machine learning stages due to the high computational costs. To decrease the computational cost many methods were proposed in the literature such as data condensing, feature selection, and filtering. Although clustering methods are generally employed to divide samples into groups, another way of data condensing is by determining ideal exemplars (or prototypes), which can be used instead of the whole dataset. In this study, first the efficiency of traditional data condensing by clustering approach was confirmed according to obtained accuracies and condensing ratios in 9 different synthetic or real batch datasets. This approach was then improved to be employed in time-ordered datasets. In order to validate the proposed approach, 23 different real time-ordered datasets were used in experiments. Achieved mean RMSEs were 0.27 and 0.29 by employing the condensed (mean condensed ratio was 97.17%) and the whole datasets, respectively. Obtained results showed that higher accuracy rates and condensing ratios were achieved by the proposed approach.Öğe A new record and three little-known Eupithecia Curtis species from Turkey (Lepidoptera: Geometridae)(TÜBİTAK, 2017-05-23) Seven, ErdemIn this paper, Eupithecia opistographata Dietze, 1906 is reported as new for the fauna of Turkey, and three rare species (E. brunneata Staudinger, 1900; E. dearmata Dietze, 1904; and E. marasa Wehrli, 1932) are presented as second records on the basis of specimens collected in the mountainous areas of Siirt Province and Şirvan District, southeastern Turkey. The adults and the male genitalia of the species are illustrated.Öğe A fast feature selection approach based on extreme learning machine and coefficient of variation(TÜBİTAK, 2017-07-30) Ertuğrul, Ömer Faruk; Tağluk, Mehmet EminFeature selection is the method of reducing the size of data without degrading their accuracy. In this study, we propose a novel feature selection approach, based on extreme learning machines (ELMs) and the coefficient of variation (CV). In the proposed approach, the most relevant features are identified by ranking each feature with the coefficient obtained through ELM divided by CV. The achieved accuracies and computational costs, obtained with the use of features selected via the proposed approach in 9 classification and 26 regression benchmark data sets, were compared to those obtained with all features, as well as those obtained with the features selected by a wrapper and a filtering method. The achieved accuracy values obtained with the proposed approach were generally higher than when using all features. Furthermore, high feature reduction ratios were obtained with the proposed approach, including the achieved feature reduction ratios in epilepsy, liver, EMG, shuttle, and abalone. Stock data sets were 90.48%, 90%, 70.59%, 66.67%, 75%, and 77.78%, respectively. This approach is an extremely fast process that is independent of the employed machine-learning methods.Öğe Geochemistry of the cretaceous-tertiary (K/T) transition clays in the Southeastern Turkey(Komitet Zrównoważonej Gospodarki Surowcami Mineralnymi PAN, 2024-04-17) Tetiker, SemaThe mineralogy and chemistry of Upper Cretaceous -Lower Paleocene claystone sediments from Mardin and Batman, southeastern Turkey, were analyzed. The main mineral paragenesis in the Upper Cretaceous member formed chlorite-smectite (C -S) and illite, while the Lower Paleocene member occurred of chlorite -vermiculite (C -V) and vermiculite minerals. The clays were silica -poor but indicated high values of Al, Fe, Mg, Cr, Ni, V, and Zr. Lower contents of the alkali elements (Na, Ca, Mg, K) of the clayey sediments suggests a relatively denser weathering of the source area. The mineralogical compositions, major element ratios, trace, and rare earth element (REE) contents of the sediments show that the Upper Cretaceous member consists of materials with a mainly felsic source lithology, while relatively contributions from basic sources are found in the Lower Paleocene unit. A comparison of the major and trace element contents of the phyllosilicate/clay minerals with the members revealed that the patterns of the clays were different from each other, although the enrichments/decreases varied depending on the origin (basement rocks or detrital) of the derived rocks, minerals, and elements. REE content of clays increased from detrital to phyllosilicate/clay minerals of chemical/diagenetic/neoformation origin during the Lower Paleocene. During the Cretaceous and Tertiary periods, local or regional geodynamic and diagenetic events largely governed the rock sedimentation processes and provenance variations amongst Germav Formation members.
