Ortak Dersler Bölümü

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Analysis and Mathematical Computation of Some Dynamic Function for Strontium Stannate
(Taylor & Francis Ltd, 2021) Askun, Ali Riza; 56475; 01. Çankaya Üniversitesi; 09. Rektörlük; 09.01. Ortak Dersler Bölümü
The frequency and full width at half maximum (FWHM) data of the A(g) Raman modes (95.4, 231.4 and 263.2 cm(-1)) in strontium stannate crystal have been analyzed using the Balkanski model and the fitting parameters were determined. Also, the isobaric Gruneisen parameter of A(g) Raman modes studied here was computed below the room temperature. This computation was performed from the unit cell volume and the observed frequency data of this crystal. Finally, values of the activation energy were extracted close to the structural phase transition temperatures of 160 and 265 K using the observed FWHM data of strontium stannate.
Analysis and Mathematical Computation of Some Dynamic Functions for the Guanidine Zinc Sulfate
(Taylor & Francis Ltd, 2021) Askun, A. R.; Kiraci, A.; 56475; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
A power-law formula with a critical exponent alpha was used to analyze the anomalous behavior of the specific heat for guanidine zinc sulfate (GZS) crystal close to the phase transition temperature of T-c = 178.4 K. The obtained values of 0.13 and 0.14 for alpha below (T < T-c) and above (T> T-c) the phase transition temperature, respectively, were almost the same value of 0.13 (1/8) that predicted from the 3-D (sing model. Also, the internal energy U, the entropy S and the free energy G of this crystal were calculated as a function of temperature dose to the phase transition temperature of T-c = 178.4 K.
Citation - WoS: 2
Citation - Scopus: 3
Analysis of the Integrated Intensity of the Central Peaks Calculated as a Function of Temperature in the Ferroelectric Phase of Lithium Tantalate
(Vinca inst Nuclear Sci, 2018) Yurtseven, Hamit; Kiraci, Ali; 42475; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
The integrated intensity of the central peak is calculated as a function of temperature in the ferroelectric phase (T < T-C) of nearly stoichiometric LiTaO3. This calculation is performed using the temperature dependence of the order parameter obtained from the mean field theory at temperatures lower than the transition temperature T-C (T-C = 963 K) of this crystal. The calculated values of the order parameter (squared) are fitted to the integrated intensity of the central peaks as observed from the Raman and Brillouin scattering experiments as reported in the literature in the ferroelectric phase of nearly stoichiometric LiTaO3. Our results are in good agreement with the observed behavior of LiTaO3 crystal. Because of the applications of LiTaO3 in several academic disciplines including the material science and thermal science, it is beneficial to investigate dynamic properties of this crystal such as the damping constant, inverse relaxation time and the activation energy as also we studied here.
Analysis of the Specific Heat and the Free Energy and Calculation of the Entropy and the Internal Energy of [N(ch3)4]2mnbr4 Close To the Phase Transition
(Taylor & Francis Ltd, 2021) Kiraci, A.; 42475; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
The critical behavior of the specific heat and the Gibbs free energy of [N(CH3)(4)](2)MnBr4 was analyzed using the 'sing model close to the phase transition temperature of T-c = 276.5 K. Obtained value of alpha=0.02 from the Gibbs free energy and from the specific heat approximately 2.0 K and 1.4 K, respectively, below Tc (ferroelastic phase) and also deduced value of alpha= 0.04 from the specific heat approximately 0.3 K above T-c (paraelastic phase) can be compared with that predicted from mean field theory (alpha = 0). Also, the entropy and the internal energy of this crystal were predicted.
Citation - WoS: 3
Citation - Scopus: 2
Calculation of the Infrared Frequencies as a Function of Temperature Using the Volume Data in the Ferroelectric Phase of Nano2
(Taylor & Francis Ltd, 2014) Kiraci, A.; Yurtseven, H.; 42475; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
We calculate the temperature dependence of the infrared frequencies of the TO and LO modes with the symmetries of A(1), B-1 and B-2 mainly in the ferroelectric phase of NaNO2. This calculation is carried out using the volume dependence of the infrared frequencies through the mode Gruneisen parameter in this crystal. The volume dependences of the infrared frequencies are fitted to the observed frequencies by using constant mode Gruneisen parameter in the ferroelectric phase of NaNO2. Our results show that this method of calculating the infrared frequencies describes the observed behaviour of NaNO2 adequately.
Citation - WoS: 21
Citation - Scopus: 25
Classification Models Based on Tanaka's Fuzzy Linear Regression Approach: the Case of Customer Satisfaction Modeling
(Ios Press, 2010) Sekkeli, Gizem; Koksal, Gulser; Batman, Inci; Bayrak, Ozlem Turker; 56416; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
Fuzzy linear regression (FLR) approaches are widely used for modeling relations between variables that involve human judgments, qualitative and imprecise data. Tanaka's FLR analysis is the first one developed and widely used for this purpose. However, this method is not appropriate for classification problems, because it can only handle continuous type dependent variables rather than categorical. In this study, we propose three alternative approaches for building classification models, for a customer satisfaction survey data, based on Tanaka's FLR approach. In these models, we aim to reflect both random and fuzzy types of uncertainties in the data in different ways, and compare their performances using several classification performance measures. Thus, this study contributes to the field of fuzzy classification by developing Tanaka based classification models.
Citation - WoS: 3
Citation - Scopus: 4
Damping Constant and the Inverse Relaxation Time Calculated as a Function of Pressure Using the X-Ray Diffraction Data Close To the Cubic-Tetragonal Phase Transition in Srtio3
(Taylor & Francis Ltd, 2019) Kiraci, A.; Yurtseven, H.; 42475; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
The damping constant is calculated as a function of pressure at room temperature using the normalized intensity as an order parameter near the cubic-tetragonal phase transition in SrTiO3. The observed X-ray diffraction data are used for the normalized intensities to calculate the damping constant () from the pseudospin-phonon (PS) coupled model and the energy fluctuation (EF) model, which is fitted to the observed FWHM data from the literature for comparison. Using the calculated values, the pressure dependence of the inverse relaxation time () is predicted close to the cubic-tetragonal phase transition in SrTiO3. Our calculated damping constant from both models explains the observed FWHM satisfactorily and our prediction of the inverse relaxation time can also be compared with the experimental measurements when they are available in the literature.
Citation - WoS: 2
Citation - Scopus: 1
Inter-Laboratory Comparison Scheme for Fuel Sector, Labkar in Turkey
(Springer, 2009) Bayrak, Ozlem Turker; Okandan, Ender; Uckardes, Hale; 56416; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
Fuel sector is one of the powerful sectors in Turkish industry. The implementation of a new law for regulating the fuel sector had enforced the quality control of fuels sold to public. This resulted in several accredited fuel-testing laboratories to emerge. Thus, a scheme to evaluate their proficiency in measurements became an important requirement. The inter-laboratory comparison scheme LABKAR for gasoline, diesel oil, LPG, lubricating oil and biodiesel samples have evolved to fulfill this need. In this paper, LABKAR is introduced; the results obtained from the program are analyzed and discussed. The kernel densities of the participants' results show that the use of robust mean as a consensus value is appropriate for fuel samples. Although the number of rounds is not enough to derive strict conclusions, it is seen that the performance of the scheme based on the standard deviations and coefficient of variations is improving in each round. It has been observed that the number of laboratories receiving "action" or "warning" is decreasing, which indicates that they are benefiting from the scheme.
Investigation of the Anomalous Behavior of the Linewidth (Damping Constant) for the Raman Ag Modes in Srsno3 Ceramic
(Taylor & Francis Ltd, 2022) Kiraci, A.; 42475; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
The anomalous behavior of the linewidth (damping constant) for the Raman A(g) modes of 223 cm(-1) and 260 cm(-1) that contribute to the phase transition mechanism of SrSnO3 ceramic close to the phase transition temperatures of T-C1= 650 K and T-C2= 530 K, respectively, was calculated as function of temperature from the pseudospin-phonon coupled (PS) and the energy fluctuation (EF) models below (T < T-C) and above (T > T-C) the phase transition temperatures of T-C1 and T-C2. For this calculation, the frequency shift of these modes were associated as the order parameter and disorder parameter below and above T-C, respectively. Our results are in good agreement with the observed linewidth of these 223 cm(-1) and 260 cm(-1) Raman A(g) modes. In addition, these two models (PS and EF) were used to deduce the values of the activation energy for SrSnO3 ceramic below and above the phase transition temperatures of T-C1 and T-C2.
Citation - WoS: 3
Citation - Scopus: 7
Modeling of Infographic Generation Process as a Learning Strategy at the Secondary School Level Based on the Educational Design Research Method
(Turkish Education Assoc, 2018) Akkoyunlu, Buket; Kibar, Pinar Nuhoglu; 8539; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
The study aimed to model an infographic design process for the use of infographics as a learning strategy at the secondary school level. A progressive model was suggested in line with a hypothetical perspective regarding the infographic generation process in order to enable learners to resolve and visualize complex information. Using educational design research methodology, the research took place over three meso cycles each comprised of micro cycles: the first two meso cycles included the micro-cycles of analysis and exploration, design and construction and evaluation and reflection and the third meso cycle the evaluation and reflection micro cycle. The study was conducted in collaboration with Information Technology, Science and Technology and Visual Arts teachers and with the participation of 18 7th grade students in the first meso cycle and 19 7th-grade students in the second meso cycle. The infographic design process and the reached infographic design levels were evaluated using the infographic design rubric, reflection forms and focus group interview. Based on the evaluation results obtained at the end of the first two meso cycles, the infographic design process was redesigned and developed. The infographic design process was designed to include the steps of content acquisition, infographic design information, content preparation, content generation, visual design generation, draft generation and digital design in the first meso cycle. In accordance with evaluations, the second meso cycle preserved these steps and implemented a spiral structure to replace the progressive structure of the first meso cycle. Sub-stages were added to meet the determined needs to the infographic design process, training activities were increased and a greater length of time was given for the digital design step. In accordance with the reflection obtained throughout the process, laboratory computers used in the design process in the first cycle were replaced with the students' own tablets in the second. The infographic design levels and reflections reached in the second meso cycle indicated that the arrangements made in the infographic design process developed the process. At the end of the comprehensive evaluation undertaken in the third meso cycle, a conclusion was reached that the collaboration between different fields, infographic design experience and the use of learners' own instruments was significant. This study can be distinguished from other relevant studies as it presents a comprehensive process model in accordance with the educational design research method which contains applications within itself regarding the implementation of infographic design strategy in the learning process.
Citation - WoS: 4
Citation - Scopus: 4
Order-Disorder Transition in the Ferroelectric Litao3
(Taylor & Francis Ltd, 2019) Yurtseven, Hamit; Kiraci, Ali; 42475; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
The temperature dependences of the damping constant and the relaxation time are calculated by using the Raman frequencies of a* and the lowest A(1) (TO) phonons in the ferroelectric phase close to the ferroelectric-paraelectric transition in LiTaO3 (T-C = 963 K). Both calculations are performed by considering the frequency as an order parameter for the pseudospin-phonon (PS) and the energy fluctuation (EF) models using the observed data from the literature. Values of the activation energies of this crystal are also deduced by using both models in this crystal. Our results show that the PS and EF models can describe the observed behavior adequately for the order-disorder transition in LiTaO3.
Citation - Scopus: 1
Phenomenological Approaches on the Nd³⁺ Doped Ferroelectric Labgeo5
(Taylor & Francis Ltd, 2021) Kiraci, A.; Yurtseven, Hamit; Kara, N.; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
Two phenomenological models, namely the compressible Ising model and Landau model, have been used to analyze the specific heat and the dielectric constant data, respectively for the pure and Nd3+ doped LaBGeO5 (LBG) crystals. The critical exponent of the specific heat was extracted in both ferroelectric and paraelectric phases of the crystals studied here within the temperature intervals of [T - T-C vertical bar < 4 K. The extracted values of the critical exponent were then used to predict some thermodynamic quantities such as the enthalpy, entropy, and the Gibbs free energy. Regarding the analysis of dielectric constant data within the framework of the Landau theory, the observed values of the birefringence were associated with the order parameter below the transition temperature T-c. The Landau coefficients a(0) and a(4) were determined. Our results indicate a second-order phase transition mechanism.
Citation - WoS: 2
Citation - Scopus: 2
Phenomenological Study of Manganese Antimonite Close To the Neel Temperature
(Ieee-inst Electrical Electronics Engineers inc, 2021) Kiraci, Ali; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
The anomalous behavior of the frequency f and specific heat C-p data for the new layered trigonal (P (3) over bar 1m) form of manganese antimonite (MnSb2O6) was analyzed by means of the power-law relations with the critical exponent alpha in the vicinity of the Neel temperature of T-N= 8.0 K. While the extracted values of a from both f and C-p below T-N (the same value of 0.06) match exactly the value 1/16 (= 0.06) predicted from the three-dimensional (3-D) Ising model, the extracted value of 0.65 from the C-p data above T-N is much higher than the predicted value of 1/8 (= 0.13) from the 3-D Ising model. As an extension of this work, the temperature dependence of the muon-spin relaxation rate (damping constant) lambda of MnSb2O6 was calculated from the pseudospin-phonon-coupled (PS) model and the energy fluctuation (EF) model below T-N. Our results are in good agreement with the data. In addition, the activation energy was calculated from the predicted values of. from both PS and EF models for MnSb2O6. Our results indicate an order-disorder-type transition at T-N = 8.0 K for MnSb2O6.
Citation - WoS: 2
Citation - Scopus: 3
A Phenomenological Study on Ferroelectric Β-Glycine
(Taylor & Francis Ltd, 2021) Kiraci, A.; 42475; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
The anomalous behavior of the specific heat for beta-glycine was analyzed in terms of the compressible Ising model approximately 5 K below and above the ferrelectric-paraelectric phase transition temperature of T-C =252 K. The obtained value of the critical exponent alpha =0.12 in the ferroelectric phase (T < TC) was consistent with that predicted from the 3-d Ising model (alpha =0.13), while the obtained value of alpha =0.32 in the paraelectric phase (T > TC) was consistent with that predicted from the 2-d potts model (alpha =0.30). Some thermodynamic quantities such as the internal energy, the entropy and the free energy of beta-glycine were then predicted in terms of these extracted values of the critical exponents close to the phase transition temperature of TC. Our calculated values of the thermodynamic quantities are in good agreement with the observed data.
Citation - WoS: 1
Citation - Scopus: 1
Pressure Dependence of the Raman Frequency Calculated From the Volume Data Close To the Ferroelectric-Paraelectric Transition in Pbtio3
(Taylor & Francis Ltd, 2017) Kiraci, Ali; Yurtseven, Hamit; 42475; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
We calculate the pressure dependence of the Raman frequencies of some Raman modes by using the observed volume data through the mode Gruneisen parameters for the ferroelectri-paraelectric transition in PbTiO3. The mode Gruneisen parameters which we have determined using the observed Raman frequencies for the soft modes, increase considerably with increasing pressure toward the transition pressure (PC similar to 11 GPa) from the tetragonal (ferroelectric) to the cubic (paraelectric) phase in PbTiO3. Variation of the mode Gruneisen parameter with the pressure is rather smooth for the other Raman modes studied as compared to the drastic change at PC for the soft modes in this ferroelectric material. Raman frequencies (energy shifts) of the modes which we have calculated, decrease from the ferroelectric to the paraelectric phase with the exception of the optical modes of E(3LO) and E(3TO) whose Raman frequencies increase with increasing pressure. This decrease and/or increase in the energy shifts for the Raman modes which we have calculated as also observed experimentally, shows a continuous manner, indicating a second order character rather that the first order transition from the tetragonal to the cubic phase in PbTiO3.

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