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Ozbek M.E.,Zmir Institute of Technology | Savaci F.A.,Zmir Institute of Technology
Expert Systems with Applications | Year: 2011

Fundamental frequency or pitch determination is one of the main issues in the transcription of music. In this paper, we determined the fundamental frequencies of isolated musical instrument samples by computing the correntropy functions. As the correntropy function depends on kernel methods, we demonstrated its performance using various kernel sizes. We presented the better resolution of the correntropy function than the conventional and the summary autocorrelation functions by calculating the full-width-at-half-maximum of the peaks of the functions. The superiority was confirmed for the samples of 20 different instruments based on the average width of the peaks. © 2011 Published by Elsevier Ltd.

Heerd D.,Jacobs University Bremen | Yegin S.,Jacobs University Bremen | Yegin S.,Ege University | Tari C.,Zmir Institute of Technology | Fernandez-Lahore M.,Jacobs University Bremen
Food and Bioproducts Processing | Year: 2012

A comparative evaluation of three Aspergillus species according to their pectinase production in solid-state fermentation was performed. Solid-state fermentation offers several potential advantages for enzyme production by fungal strains. Utilization of agricultural by-products as low-cost substrates for microbial enzyme production resulted in an economical and promising process. The pectinolytic enzyme activities of two Aspergillus sojae strains were compared to a known producer, Aspergillus niger IMI 91881, and to A. sojae ATCC 20235, which was re-classified as Aspergillus oryzae. Evaluation of polymethylgalacturonase and polygalacturonase activity was performed as well as exo- vs. endo-enzyme activity in the crude pectinase enzyme-complex of the mentioned strains. Furthermore, a plate diffusion assay was applied to determine the presence and action of proteases in the crude extracts. A. sojae ATCC 20235 with highest polymethylgalacturonase activity and highest polygalacturonase activity both exo- and endo-enzyme activity, is a promising candidate for industrial pectinase production, a group of enzymes with high commercial value, in solid-state fermentation processes. Beside the enzymatic assays a protein profile of each strain is given by SDS-PAGE electrophoresis and in addition species-specific zymograms for pectinolytic enzymes were observed, revealing the differences in protein pattern of the A. sojae strains to the re-classified A. oryzae. © 2011 The Institution of Chemical Engineers.

Horzum N.,Zmir Institute of Technology | Tascioglu D.,Zmir Institute of Technology | Okur S.,Zmir Institute of Technology | Demir M.M.,Zmir Institute of Technology
Talanta | Year: 2011

Zinc oxide (ZnO) based fibers with a diameter of 80-100 nm were prepared by electrospinning. Polyvinyl alcohol (PVA) and zinc acetate dihydrate were dissolved in water and the polymer/salt solution was electrospun at 2.5 kV cm-1. The resulting electrospun fibers were subjected to calcination at 500 °C for 2 h to obtain ZnO-based fibers. Humidity sensing properties of the fiber mats were investigated by quartz crystal microbalance (QCM) method and electrical measurements. The adsorption kinetics under constant relative humidity (RH) between 10% and 90% were explained using Langmuir adsorption model. Results of the measurements showed that ZnO-based fibers were found to be promising candidate for humidity sensing applications at room temperature. © 2011 Elsevier B.V.

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