Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 13

Search results for: Sevil Yucel

13 Polymerisation Shrinkage of Light−Cured Hydroxyapatite (HA)−Reinforced Dental Composites

Authors: Bilge S. Oduncu, Sevil Yucel, Ismail Aydin, Isil D. Sener, Gokhan Yamaner

Abstract:

The dental composites are preferably used as filling materials due to their esthetic appearances. Nevertheless one of the major problems, during the application of the dental composites, is shape change named as “polymerisation shrinkage" affecting clinical success of the dental restoration while photo-polymerisation. Polymerisation shrinkage of composites arises basically from the formation of a polymer due to the monomer transformation which composes of an organic matrix phase. It was sought, throughout this study, to detect and evaluate the structural polymerisation shrinkage of prepared dental composites in order to optimize the effects of various fillers included in hydroxyapatite (HA)-reinforced dental composites and hence to find a means to modify the properties of these dental composites prepared with defined parameters. As a result, the shrinkage values of the experimental dental composites were decreased by increasing the filler content of composites and the composition of different fillers used had effect on the shrinkage of the prepared composite systems.

Keywords: Dental composites, hydroxyapatite (HA), BisGMA, shrinkage.

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12 Swelling Behavior and Cytotoxicity of Maleic Acid Grafted Chitosan

Authors: Sevil Yucel, Zafer Omer Ozdemir, Cem Kesgin, Pinar Terzioglu, Simten Unlu, Yagmur Erdogan, Kubra Pusat

Abstract:

Chitosan is an attractive polysaccharide obtained by deacetylation of an abundant natural biopolymer called chitin. Chitin and chitosan are excellent materials. To improve the potential of chitin and chitosan modification is needed. In the present study, grafting of maleic acid on to chitosan by cerium ammonium nitrate in acetic acid solution was investigated with use of a microwave and reflux system. The grafted chitosan was characterized by using a Fourier-transform infrared spectrometry. The solubility and swelling behavior of grafted chitosans were determined in acetate buffer (pH 3.6), citrophosphate buffer (pH 5.6 and pH 7.0), and boric buffer (pH 9.2) solutions. The sample obtained by microwave system with use of a chitosan/maleic anhydride/ceric ammonium nitrate 0.2/3.922/0.99 gram of raw material within 30 minute showed the maximum swelling ratio (13.6) in boric buffer solution.

Keywords: Chitosan, cytotoxicity, grafted, maleic acid, swell.

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11 The Effects of Signal Level of the Microwave Generator on the Brillouin Gain Spectrum in BOTDA and BOTDR

Authors: M. Yucel, M. Yucel, N. F. Ozturk, H. H. Goktas, C. Gemci, F. V. Celebi

Abstract:

In this study, Brillouin Gain Spectrum (BGS) is experimentally analyzed in the Brillouin Optical Time Domain Reflectometry (BOTDR) and Brillouin Optical Time Domain Analyzer (BOTDA). For this purpose, the signal level of the microwave generator is varied and the effects of BGS are investigated. In the setups, 20 km conventional single mode fiber is used to both setups and laser wavelengths are selected around 1550 nm. To achieve best results, it can be used between 5 dBm to 15 dBm signal level of microwave generator for BOTDA and BOTDR setups.

Keywords: Microwave signal level, Brillouin gain spectrum, BOTDA, BOTDR.

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10 Differentiation of Cancerous Prostate tissue from Non-Cancerous Prostate tissue by using Elastic Light Single-Scattering Spectroscopy: A Feasibility Study

Authors: T. Denkçeken, M. Canpolat, Đ. Bassorgun, S. Yücel, M.A. Çiftçioğlu, M. Baykara Murat Canpolat , Tuba Denkçeken , Đbrahim Bassorgun , Selçuk Yücel , M. Akif Çiftçioğlu , Mehmet Baykara

Abstract:

Elastic light single-scattering spectroscopy system with a single optical fiber probe was employed to differentiate cancerous prostate tissue from non-cancerous prostate tissue ex-vivo just after radical prostatectomy. First, ELSSS spectra were acquired from cancerous prostate tissue to define its spectral features. Then, spectra were acquired from normal prostate tissue to define difference in spectral features between the cancerous and normal prostate tissues. Of the total 66 tissue samples were evaluated from nine patients by ELSSS system. Comparing of histopathology results and ELSSS measurements revealed that sign of the spectral slopes of cancerous prostate tissue is negative and non-cancerous tissue is positive in the wavelength range from 450 to 750 nm. Based on the correlation between histopathology results and sign of the spectral slopes, ELSSS system differentiates cancerous prostate tissue from non- cancerous with a sensitivity of 0.95 and a specificity of 0.94.

Keywords: Diagnosis, prostatic neoplasm, prostatectomy, spectrum analysis

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9 Legal Arrangement on Media Ownership and the Case of Turkey

Authors: Sevil Yıldız

Abstract:

In this study, we will touch upon the legal arrangements issued in Turkey for prevention of condensation and for ensuring pluralism in the media. We will mention the legal arrangements concerning the regulatory and supervisory authority, namely the Radio and Television Supreme Council, for the visual and auditory media. In this context; the legal arrangements, which have been introduced by the Law No 6112 on the Establishment of Radio and Television Enterprises and Their Media Services in relation to the media ownership, will be reviewed through comparison with the Article 29 of the repealed Law No 3984.

Keywords: Media ownership, legal arrangements, the case for Turkey.

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8 Enhanced Face Recognition with Daisy Descriptors Using 1BT Based Registration

Authors: Sevil Igit, Merve Meric, Sarp Erturk

Abstract:

In this paper, it is proposed to improve Daisy Descriptor based face recognition using a novel One-Bit Transform (1BT) based pre-registration approach. The 1BT based pre-registration procedure is fast and has low computational complexity. It is shown that the face recognition accuracy is improved with the proposed approach. The proposed approach can facilitate highly accurate face recognition using DAISY descriptor with simple matching and thereby facilitate a low-complexity approach.

Keywords: Face Recognition, Daisy Descriptor, One-Bit Transform, Image Registration.

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7 Freedom of Expression and Its Restriction in Audio Visual Media

Authors: Sevil Yildiz

Abstract:

Audio visual communication is a type of collective expression. Due to inform the masses, give direction to opinions, and establish public opinion, audio visual communication must be subjected to special restrictions. This has been stipulated in both the Constitution and the European Human Rights Agreement. This paper aims to review freedom of expression and its restriction in audio visual media. For this purpose, the authorization of the Radio and Television Supreme Council to impose sanctions as an independent administrative authority empowered to regulate the field of audio visual communication has been reviewed with regard to freedom of expression and its limits.

Keywords: Audio visual media, freedom of expression, its limits, Radio and Television Supreme Council.

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6 Human Interactive E-learning Systems using Head Posture Images

Authors: Yucel Ugurlu

Abstract:

This paper explains a novel approach to human interactive e-learning systems using head posture images. Students- face and hair information are used to identify a human presence and estimate the gaze direction. We then define the human-computer interaction level and test the definition using ten students and seventy different posture images. The experimental results show that head posture images provide adequate information for increasing human-computer interaction in e-learning systems.

Keywords: E-learning, image segmentation, human-presence, gaze-direction, human-computer interaction, LabVIEW

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5 Numerical Simulation of Flow and Combustionin an Axisymmetric Internal Combustion Engine

Authors: Nureddin Dinler, Nuri Yucel

Abstract:

Improving the performance of internal combustion engines is one of the major concerns of researchers. Experimental studies are more expensive than computational studies. Also using computational techniques allows one to obtain all the required data for the cylinder, some of which could not be measured. In this study, an axisymmetric homogeneous charged spark ignition engine was modeled. Fluid motion and combustion process were investigated numerically. Turbulent flow conditions were considered. Standard k- ε turbulence model for fluid flow and eddy break-up model for turbulent combustion were utilized. The effects of valve angle on the fluid flow and combustion are analyzed for constant air/fuel and compression ratios. It is found that, velocities and strength of tumble increases in-cylinder flow and due to increase in turbulence strength, the flame propagation is faster for small valve angles.

Keywords: CFD simulation, eddy break-up model, k-εturbulence model, reciprocating engine flow and combustion.

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4 Reflections of Prospective Teachers Toward a Critical Thinking-Based Pedagogical Course: A Case Study

Authors: Ahmet Ok, Banu Yücel Toy

Abstract:

Promoting critical thinking (CT) in an educational setting has been appraised in order to enhance learning and intellectual skills. In this study, a pedagogical course in a vocational teacher education program in Turkey was designed by integrating CT skill-based strategies/activities into the course content and CT skills were means leading to intended course objectives. The purpose of the study was to evaluate the importance of the course objectives, the attainment of the objectives, and the effectiveness of teachinglearning strategies/activities from prospective teachers- points of view. The results revealed that although the students mostly considered the course objectives important, they did not feel competent in the attainment of all objectives especially in those related to the main topic of Learning and those requiring higher order thinking skills. On the other hand, the students considered the course activities effective for learning and for the development of thinking skills, especially, in interpreting, comparing, questioning, contrasting, and forming relationships.

Keywords: Critical thinking, critical thinking-based instruction, higher order thinking skills, teacher education

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3 Radio and Television Supreme Council as a Regulatory Board

Authors: Sevil Yildiz

Abstract:

In parallel, broadcasting has changed rapidly with the changing of the world at the same area. Broadcasting is also influenced and reshaped in terms of the emergence of new communication technologies. These developments have resulted a lot of economic and social consequences. The most important consequences of these results are those of the powers of the governments to control over the means of communication and control mechanisms related to the descriptions of the new issues. For this purpose, autonomous and independent regulatory bodies have been established by the state. One of these regulatory bodies is the Radio and Television Supreme Council, which to be established in 1994, with the Code no 3984. Today’s Radio and Television Supreme Council which is responsible for the regulation of the radio and television broadcasts all across Turkey has an important and effective position as autonomous and independent regulatory body. The Radio and Television Supreme Council acts as being a remarkable organizer for a sensitive area of radio and television broadcasting on one hand, and the area of democratic, liberal and keep in mind the concept of the public interest by putting certain principles for the functioning of the Board control, in the context of media policy as one of the central organs, on the other hand. In this study, the role of the Radio and Television Supreme Council is examined in accordance with the Code no 3894 in order to control over the communication and control mechanisms as well as the examination of the changes in the duties of the Code No. 6112, dated 2011.

Keywords: Regulatory Boards, Radio and Television Supreme Council.

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2 Experimental and Numerical Simulation of Fire in a Scaled Underground Station

Authors: Nuri Yucel, Muhammed Ilter Berberoglu, Salih Karaaslan, Nureddin Dinler

Abstract:

The objective of this study is to investigate fire behaviors, experimentally and numerically, in a scaled version of an underground station. The effect of ventilation velocity on the fire is examined. Fire experiments are simulated by burning 10 ml isopropyl alcohol fuel in a fire pool with dimensions 5cm x 10cm x 4 mm at the center of 1/100 scaled underground station model. A commercial CFD program FLUENT was used in numerical simulations. For air flow simulations, k-ω SST turbulence model and for combustion simulation, non-premixed combustion model are used. This study showed that, the ventilation velocity is increased from 1 m/s to 3 m/s the maximum temperature in the station is found to be less for ventilation velocity of 1 m/s. The reason for these experimental result lies on the relative dominance of oxygen supply effect on cooling effect. Without piston effect, maximum temperature occurs above the fuel pool. However, when the ventilation velocity increased the flame was tilted in the direction of ventilation and the location of maximum temperature moves along the flow direction. The velocities measured experimentally in the station at different locations are well matched by the CFD simulation results. The prediction of general flow pattern is satisfactory with the smoke visualization tests. The backlayering in velocity is well predicted by CFD simulation. However, all over the station, the CFD simulations predicted higher temperatures compared to experimental measurements.

Keywords: Fire, underground station, flame propagation, CFDsimulation, k-ω SST turbulence model, non-premixed combustionmodel.

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1 Characterization of Biocomposites Based on Mussel Shell Wastes

Authors: Suheyla Kocaman, Gulnare Ahmetli, Alaaddin Cerit, Alize Yucel, Merve Gozukucuk

Abstract:

Shell wastes represent a considerable quantity of byproducts in the shellfish aquaculture. From the viewpoint of ecofriendly and economical disposal, it is highly desirable to convert these residues into high value-added products for industrial applications. So far, the utilization of shell wastes was confined at relatively lower levels, e.g. wastewater decontaminant, soil conditioner, fertilizer constituent, feed additive and liming agent. Shell wastes consist of calcium carbonate and organic matrices, with the former accounting for 95-99% by weight. Being the richest source of biogenic CaCO3, shell wastes are suitable to prepare high purity CaCO3 powders, which have been extensively applied in various industrial products, such as paper, rubber, paints and pharmaceuticals. Furthermore, the shell waste could be further processed to be the filler of polymer composites. This paper presents a study on the potential use of mussel shell waste as biofiller to produce the composite materials with different epoxy matrices, such as bisphenol-A type, CTBN modified and polyurethane modified epoxy resins. Morphology and mechanical properties of shell particles reinforced epoxy composites were evaluated to assess the possibility of using it as a new material. The effects of shell particle content on the mechanical properties of the composites were investigated. It was shown that in all composites, the tensile strength and Young’s modulus values increase with the increase of mussel shell particles content from 10 wt% to 50 wt%, while the elongation at break decreased, compared to pure epoxy resin. The highest Young’s modulus values were determined for bisphenol-A type epoxy composites.

Keywords: Biocomposite, epoxy resin, mussel shell, mechanical properties.

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