Frat University

Of, Turkey

Frat University

Of, Turkey
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In this paper, ansatz approach with the Jacobi elliptic functions is used to construct the solutions for the Zhiber–Shabat and related equation: Liouville equation, Dodd–Bullough–Mikhailov (DBM) equation, sinh–Gordon equation, and Tzitzeica–Dodd–Bullough (TDB) equation. Cnoidal, snoidal, triangular and periodic wave solutions for these equations are obtained. The constraint relations between the model coefficients and the damping coefficient for existence of soliton solutions are derived. The remarkable properties of the obtained solutions are showed in four interesting figures. © 2017 Elsevier GmbH

Selimefendigil F.,Celal Bayar University | Oztop H.F.,Frat University
International Communications in Heat and Mass Transfer | Year: 2012

In this study, heat transfer from a square cavity in the presence of a thin inclined adiabatic fin is estimated using inputs-outputs generated from a CFD code with a fuzzy based identification procedure. The Reynolds number based on cavity length is 300 and the Richardson number is varied between 1 and 30. The top and bottom walls of the cavity are kept at constant temperature while the vertical walls are assumed to be adiabatic. The fin height, fin inclination angle, and Richardson number are considered as the input and the spatial averaged Nusselt number is taken as the output for the fuzzy model. Two data sets are used. One data set which contains 45 cases is used for estimation and another data set which contains 10 cases (not used in estimation) is used for validation purposes. The predictions using fuzzy model compare well with the CFD computations. © 2012 Elsevier Ltd.

Selimefendigil F.,Celal Bayar University | Oztop H.F.,Frat University
Numerical Heat Transfer; Part A: Applications | Year: 2014

In this study, numerical investigation of mixed convection in a square cavity with ventilation ports filled with nanofluids in the presence of an adiabatic rotating cylinder is conducted. The governing equations are solved with a commercial finite element code (COMSOL). The effects of Grashof number (Gr103 to Gr105), Reynolds number (Re50 to Re300), nanoparticle volume fraction (/0 to /0.05), and cylinder rotation angle (X 5 to X5) on the flow and thermal fields are numerically studied for a range of different parameter sets. The generalized neural network (GRNN) is used to predict the thermal performance of the system. It is observed that the heat transfer increases almost linearly with increasing the nanoparticle volume fraction. The increasing rotation angle in the clockwise direction generally enhances the heat transfer. Moreover, the validation results with artificial neural networks show that generalized neural nets show better performance compared to radial basis and feed-forward networks. Copyright © Taylor & Francis Group, LLC.

In this study, an alternative fuel for diesel engines was produced from waste automobile tires by the method of pyrolysis. In order to reduce the high sulfur content of the fuel, CaO, Ca(OH) 2, and NaOH catalysts were used. In addition, effects of variables such as temperature, the catalyst ratio and the N2 flow rate on yield were investigated. The highest product yield was obtained with temperature of 500 °C and 200 cm 3/min N 2 flow rate. When compared with the products obtained from initial pyrolysis, the sulfur content of the product was found to be 34.25% lower with the utilization of 5% Ca(OH) 2 in the reaction. In order to make the sulfur content of the product closer diesel fuel, the acetic acidH 2O 2, formic acidH 2O 2 and H 2SO 2 were used in different proportions. Although, the other acids were also very effective, the use of 10% H 2SO 4 reduced sulfur content of the product by 75.27%. Thus, with 5% Ca(OH) 2 and then with addition of 10% H 2SO 4, the sulfur content of the product was reduced by 83.75%. The properties of diesel fuel (DF), liquid fuel derived from waste vehicle tires (TF), low sulfur tire fuel (LSTF) and fuel mixtures of LSTFDF were analyzed. It was found that, the density and sulfur content of LSTF fuel were slightly higher than that of diesel fuel, but other features and distillation curves were very close to diesel fuel. © 2012 Elsevier Ltd. All rights reserved.

Korpinar T.,Mus Alparslan University | Turhan E.,Frat University
International Journal of Theoretical Physics | Year: 2014

In this work, we obtain the new parametric representation for a pencil surface in Heisenberg spacetime H1, 4. We give a geometrical description of time-pencil surfaces around timelike biharmonic particle in H1, 4. Moreover, we obtain Lorentz transformations this particles. Additionally, we illustrate some pictures corresponding to different cases for second torsionless. © 2014, Springer Science+Business Media New York.

Turel Y.K.,Frat University
Computers and Education | Year: 2011

The interactive whiteboard (IWB) has become a popular technology for instructors over the last decade. Though research asserts that the IWBs facilitate learning in different ways, there is a lack of studies examining actual IWB use in classroom settings based on learners' perspectives by means of valid instruments. The purpose of this study is to develop a valid and reliable interactive whiteboard student survey in order to evaluate the IWB use based on perceptions of students who have been taught with IWBs. In establishing the theoretical base of the survey, the Technology Acceptance Model (TAM) and constructivist learning theories were considered. In addition, with respect to IWB use in classrooms, a number of studies emanated from countries such as the UK, the USA, and Australia were examined, and similar research questionnaires and findings and also reflections of students about IWBs were utilized to create an item pool. A 39-item survey was conducted among middle school students (N = 263) from the city of Istanbul in Turkey. Collected data was exposed to exploratory factor analysis and resulted in a 26-item, three-factor survey, whose factors were named as the perceived efficiency of IWB, perceived learning contribution and motivation, and the perceived negative effects of IWB. The results of the analyses illustrated that this new IWB student scale, which explains 50% of the total variance with a good level of Cronbach's Alpha coefficient (0.93) is a valid and reliable instrument designed specifically for measuring the use of IWBs in real classroom settings. Besides, theoretical foundations of interactive whiteboard use, the development process of the instrument, and results of validity and reliability analyses were discussed in detail. © 2011 Elsevier Ltd. All rights reserved.

The main purpose of this study is to examine relationships between the social abilities, perceived team learning, and the performances of students in a blended learning setting. The participants, 82 undergraduate students, worked in small teams on a research method task over one semester. The instruments used for this study included a five-factor social ability scale and a one-dimensional perceived collaborative learning scale. The results showed moderate significant relationships between students' perceived team learning scores and students' peer social presence scores as well as weaker relationships between team learning and two social ability subscales, written communication skills and instructor social presence. There appears to be an important effect of peer social presence that is linked to learning and performance. Using a blended learning model may have an important impact on increasing social interaction and learning with a team learning approach thereby helping students undertake comprehensive tasks and increase student learning. © 2016

Tuncer T.,Frat University
Nonlinear Dynamics | Year: 2016

The security of cryptographic systems depends on the unpredictability, not being regenerate and good statistical properties of the random numbers. The numbers, generated to provide the peculiarities, need to be the true random ones. Another method for generating these numbers is physical unclonable functions based on ring oscillator (RO-PUF). PUFs show susceptibility to reverse engineering, emulation, man-in-the-middle and reconfiguration attacks. In this paper, the chaotic signs which were generated from logistic map are applied to the challenge of RO-PUF in order to prevent such undesirable occurrences. Chaotic-based RO-PUF was implemented on Altera’s FPGA-based 60-nm EP4CE115F29C7 development boards by using VHDL language. The obtained random numbers passed the NIST statistical tests, accepted as standard for cryptographic applications. Additionally, the periodicity degree of the system is evaluated by the scale index method and correlations between the generated numbers are analyzed by the autocorrelation method to demonstrate their validity. The results of the developed system show that it is possible to prevent the attacks which PUFs are subjected to and increase the randomness of the obtained numbers as well. © 2016 Springer Science+Business Media Dordrecht

Ozkaynak F.,Frat University
Nonlinear Dynamics | Year: 2014

Random number generators are an important tool for cryptographic applications. In cryptographic protocol, randomness is essential properties since inadequate source of randomness can be effect security of whole system. This paper describes requirements of a robust random generator and proposes hybrid architecture to realize these requirements. Security analysis shows that output of proposed generator looks random. Therefore, proposed generator is used for cryptographic solutions. © 2014, Springer Science+Business Media Dordrecht.

Oztop H.F.,Frat University | Bayrak F.,Frat University | Hepbasli A.,Yaşar University
Renewable and Sustainable Energy Reviews | Year: 2013

Solar air heating (solar collector) is a renewable heating technology and provides heat using solar energy. With fuel costs and other factors, solar air heaters (SAHs) are getting more attention. The energetic and exergetic performance of SAHs is influenced by a number of factors. The present study reviews the previously conducted studies and applications in terms of design, performance assessment, heat transfer enhancement techniques, experimental and numerical works, thermal heat storage, effectiveness compassion and recent advances. It may be concluded that energy analysis method has been used in a number of studies while exergy analysis method has been applied to the relatively low numbers of systems. Energy efficiencies of solar air collectors reviewed varied from 47% and 89%. It is expected that this comprehensive study will be very beneficial to everyone involved or interested in the energetic and exergetic design, simulation, analysis, test and performance assessment of SAHs. © 2012 Elsevier Ltd.

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