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Permanent URI for this collectionhttps://ada.atilim.edu.tr/handle/123456789/19

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Citation Count: 15
An accurate optical gain model using adaptive neurofuzzy inference system
(National Institute of Optoelectronics, 2009) Çelebi,F.V.; Altindag,T.; Computer Engineering
This paper presents a single, simple, new and an accurate optical gain model based on adaptive neuro-fuzzy inference system (ANFIS) which combines the benefits of Artificial Neural Networks (ANNs) and Fuzzy Inference Systems (FISs). The dynamic optical gain model results are in very good agreement with the previously published experimental findings.
Citation Count: 10
Activation energy of metastable amorphous Ge₂Sb₂Te₅ from room temperature to melt
(Amer inst Physics, 2018) Muneer, Sadid; Scoggin, Jake; Dirisaglik, Faruk; Adnane, Lhacene; Cywar, Adam; Bakan, Gokhan; Gokirmak, Ali; Department of Electrical & Electronics Engineering
Resistivity of metastable amorphous Ge2Sb2Te5 (GST) measured at device level show an exponential decline with temperature matching with the steady-state thin-film resistivity measured at 858 K (melting temperature). This suggests that the free carrier activation mechanisms form a continuum in a large temperature scale (300 K - 858 K) and the metastable amorphous phase can be treated as a supercooled liquid. The effective activation energy calculated using the resistivity versus temperature data follow a parabolic behavior, with a room temperature value of 333 meV, peaking to similar to 377 meV at similar to 465 K and reaching zero at similar to 930 K, using a reference activation energy of 111 meV (3k(B)T/2) at melt. Amorphous GST is expected to behave as a p-type semiconductor at T-melt similar to 858 K and transitions from the semiconducting-liquid phase to the metallic-liquid phase at similar to 930 K at equilibrium. The simultaneous Seebeck (S) and resistivity versus temperature measurements of amorphous-fcc mixed-phase GST thin-films show linear S-T trends that meet S = 0 at 0 K, consistent with degenerate semiconductors, and the dS/dT and room temperature activation energy show a linear correlation. The single-crystal fcc is calculated to have dS/dT = 0.153 mu V/K-2 for an activation energy of zero and a Fermi level 0.16 eV below the valance band edge. (C) 2018 Author(s).
Citation Count: 0
An adaptive element division algorithm for accurate evaluation of singular and near singular integrals in 3D
(Turkiye Klinikleri, 2021) Bayindir,H.; Baranoğlu,B.; Yazici,A.; Software Engineering; Manufacturing Engineering
An adaptive algorithm for evaluation of singular and near singular integrals in 3D is presented. The algorithm is based on successive adaptive/selective subdivisions of the element until a prescribed error criteria is met. For evaluating the integrals in each subdivision, Gauss quadrature is applied. The method is computationally simple, memory efficient and can be applied for both triangular and quadrilateral elements, including the elements with nonplanar and/or curved surfaces. To assess the method, several examples are discussed. It has shown that the algorithm performs well for singular and near-singular integral examples presented in the paper and evaluates the integrals with very high accuracy. © TÜBİTAK
Citation Count: 4
Adult Education as a Stepping-Stone to Better Jobs: An Analysis of the Adult Education Survey in Turkey
(Sage Publications inc, 2018) Cilasun, Seyit Mumin; Demir-Seker, Sirma; Dincer, N. Nergiz; Tekin-Koru, Ayca; Department of Business
The objective of this article is to investigate whether adult education (AE) can be used as a tool in facilitating transitions to/in the labor market, using the cross-sectional Adult Education Survey of Turkey (2012). AE is defined as the nonformal education for individuals aged older than 25 years. The outcome of AE is measured by changing jobs for employed and finding a job for the unemployed. Concentrating on employed people, we analyze both the determinants and the outcome of participation in AE for the purpose of changing jobs; and second, concentrating on unemployed people, we analyze both the determinants and the outcome of participation in AE for the purpose of getting employed. We find that once young males who are already working participate in AE for changing work, independent of their education or how AE is financed, they can be successful in doing so. The results of the paper suggest that AE programs offered by the government can serve as a tool in increasing income of the less educated and the unemployed by facilitating their transition to the labor market.
Citation Count: 13
Alternative numerical modeling of a superconducting charge qubit as an eigenvalue problem
(Emerald Group Publishing Ltd, 2011) Canturk, Mehmet; Kurt, Erol; Askerzade, Iman N.; Computer Engineering
Purpose - The purpose of this paper is to employ an alternative numerical approach to analyze the characteristics of superconducting charge qubit based on a single Cooper pair box (SCB), also to study the influence of the bias current. Design/methodology/approach - The paper starts with the circuit model of a charge qubit system based on Josephson junction using Hamiltonian formalism. Corresponding Schrodinger eigenvalue problem with periodic boundary condition is converted to the Mathieu type eigenvalue problem. By applying finite difference technique, energy spectrum of charge qubit is obtained and the solutions in the lowest band are obtained in the form of Bloch waves whose superposition provides a wave packet to investigate the effect of bias current to the Coulomb blockade. Findings - The paper identifies a periodic tridiagonal Hermitian matrix form of the eigenvalue problem that is believed to be a special eigenvalue problem. The paper emphasizes that Schrodinger formalism is very, useful to model superconducting qubits systems. The investigations indicate that the bias current strongly influences the Coulomb blockade and expectation value of supercurrent (as well as number of Cooper pairs) are affected by gate voltage and energy scale. Research limitations/implications - In the present study, Schrodinger eigenvalue problem is time independent, therefore, current-voltage characteristics of the charge qubit system could not be considered. The solution technique applied here can also be used to apply other type of Josephson junction based qubits and circuits. Practical implications - The paper includes theoretical findings for the development of superconducting qubit that can be valuable for experimentalist. The result obtained in this study is useful for the comparison of experimental study with the expectation value of number of Cooper pairs as function of gate voltage. Working parameters of a SCB can be determined from the findings. Originality/value This paper fulfils the contribution of the numerical study of Schrodinger equation for the investigation of superconducting qubits under the influence of bias current.
Citation Count: 9
Analysing the Effects of Critique Techniques on the Success of Interior Architecture Students
(Wiley, 2018) Gul, Ciler Gozde Gunday; Afacan, Yasemin
In architectural design education, the most significant part in the curriculum is the design studio, where students learn how to design. Critique has a crucial role in the design studio, and in determining the best and most beneficial critique type for the architectural design education process. Student attitudes toward critiques and student satisfaction level with each critique technique are also significant. To that end, this article explores design studio learning by reviewing the design learning process and types of design critiques. Focusing on three critique techniques used in design education (desk critiques, pin-up critiques and group critiques), the article analyses correlations between student attitudes toward each technique and its contribution to the design process. Research was conducted with 84 third-year interior architecture students from the 2014-15 Fall semester at a university. No statistically significant differences were found between group and pin-up critiques in terms of students' preferences and their final performance scores; however, there was a statistically significant relationship between student preferences toward desk critiques and student success. Furthermore, the contribution of a critique technique to the design process was found to be highly correlated with student preference for this technique.
Citation Count: 23
Analysis of mirror neuron system activation during action observation alone and action observation with motor imagery tasks
(Springer, 2018) Cengiz, Bulent; Vuralli, Doga; Zinnuroglu, Murat; Bayer, Gozde; Golmohammadzadeh, Hassan; Gunendi, Zafer; Arikan, Kutluk Bilge; Department of Mechatronics Engineering
This study aimed to explore the relationship between action observation (AO)-related corticomotor excitability changes and phases of observed action and to explore the effects of pure AO and concurrent AO and motor imagery (MI) state on corticomotor excitability using TMS. It was also investigated whether the mirror neuron system activity is muscle-specific. Fourteen healthy volunteers were enrolled in the study. EMG recordings were taken from the right first dorsal interosseous and the abductor digiti minimi muscles. There was a significant main effect of TMS timing (after the beginning of the movement, at the beginning of motor output state, and during black screen) on the mean motor evoked potential (MEP) amplitude. Mean MEP amplitudes for AO combined with MI were significantly higher than pure AO session. There was a significant interaction between session and TMS timing. There was no significant main effect of muscle on MEP amplitude. The results indicate that corticomotor excitability is modulated by different phases of the observed motor movement and this modulation is not muscle-specific. Simultaneous MI and AO enhance corticomotor excitability significantly compared to pure AO.
Citation Count: 0
Analysis of Thermoluminescence Glow Peaks in β-Irradiated TlGaSeS Crystals
(Polish Acad Sciences inst Physics, 2016) Isik, M.; Yildirim, T.; Gasanly, N. M.; Department of Electrical & Electronics Engineering
Thermoluminescence properties of TlGaSeS layered single crystals were investigated in the temperature range of 280-720 K. Thermoluminescence glow curve exhibited three peaks with maximum temperatures of approximate to 370, 437, and 490 K. Curve fitting, initial rise and peak shape methods were used to determine the activation energies of the trapping centers. All applied methods resulted with energies around 0.82, 0.91, and 0.99 eV. Dose dependence of the thermoluminescence intensity was also examined for the doses in the range of 0.7-457.6 Gy. Peak maximum intensity of the observed peak around 370 K showed an increase up to a certain dose and then a decrease at higher doses. This non-monotonic dose dependence was discussed under the light of a reported model in which different kinds of competition between radiative and nonradiative recombination centers during excitation or heating stages of the thermoluminescence process are explained.
Citation Count: 1
Analyzing students' academic success in pre-requisite course chains: A case study in Turkey
(Tempus Publications, 2018) Karakaya,M.; Eryilmaz,M.; Ceyhan,U.O.; Information Systems Engineering; Computer Engineering
There are several principles which have been accepted as approaches to successful curriculum development. In spite of the differences in the proposed sequencing of topics, all approaches basically depend on the pre-requisite chains to implement their educational approach in the curriculum development for specifying the order of the subjects. In this research, two prerequisite chains representing two different curriculum development approaches are taken into consideration in a case study. The first research question considered is whether academic success in a follow-up course is positively related to success attained in the pre-requisite course. The second one is whether or not the selected curriculum development approach for deciding the chains has a significant impact on the academic success relationships between a pre-requisite and its follow-up course. To answer these questions, course data of 441 undergraduate students who graduated from the Atilim University between Fall 2001 and Spring 2015 semesters were collected and analyzed. The results indicate that the succes levels gained in a pre-requisite and its follow-up course are corelated. Moreover, different cirriculum development methods can affect this corelation. Thus, cirriculum developers should consider appropriate approaches to improve student success for deciding chaining courses and their contents. © 2018 TEMPUS Publications.
Citation Count: 0
ANN-assisted forecasting of adsorption efficiency to remove heavy metals
(Tubitak Scientific & Technological Research Council Turkey, 2019) Buaısha, Magdi; Balku, Şaziye; Yaman, Şeniz Özalp; Energy Systems Engineering; Chemical Engineering
In wastewater treatment, scientific and practical models utilizing numerical computational techniques suchas artificial neural networks (ANNs) can significantly help to improve the process as a whole through adsorption systems.In the modeling of the adsorption efficiency for heavy metals from wastewater, some kinetic models have been used such as pseudo first-order and second-order. The present work develops an ANN model to forecast the adsorption efficiency of heavy metals such as zinc, nickel, and copper by extracting experimental data from three case studies. To do this, we apply trial-and-error to find the most ideal ANN settings, the efficiency of which is determined by mean square error (MSE) and coefficient of determination (R2). According to the results, the model can forecast adsorption efficiency percent (AE%) with a tangent sigmoid transfer function (tansig) in the hidden layer with 10 neurons and a linear transferfunction (purelin) in the output layer. Furthermore, the Levenberg–Marquardt algorithm is seen to be most ideal for training the algorithm for the case studies, with the lowest MSE and high R2 . In addition, the experimental results and the results predicted by the model with the ANN were found to be highly compatible with each other.
Citation Count: 0
Annealing Effect on Dark Electrical Conductivity and Photoconductivity of Ga-In-Se Thin Films
(Polish Acad Sciences inst Physics, 2018) Isik, M.; Gullu, H. H.; Department of Electrical & Electronics Engineering
Dark-conductivity and photoconductivity properties of thermally evaporated Ga-In-Se (GIS) thin films were investigated in the temperature range of 80-430 K. All measurements were performed on as-grown and annealed GIS thin films at 300 and 400 degrees C to get information about the effect of the annealing temperature on the conductivity properties. Room temperature conductivity was obtained as 1.8 x 10(-8) Omega(-1) cm(-1) for as-grown films and increased to 3.6 x 10(-4) Omega(-1) cm(-1) for annealed films at 400 degrees C. Analysis of the dark-conductivity data of as-grown films revealed nearly intrinsic type of conductivity with 1.70 eV band gap energy. Temperature dependent dark conductivity curves exhibited two regions in the 260-360 and 370-430 K for both of annealed GIS films. Conductivity activation energies were found as 0.05, 0.16 and 0.05, 0.56 eV for films annealed at temperatures of 300 and 400 degrees C, respectively. The dependence of photoconductivity on illumination intensity was also studied in the range from 17 to 113 mW/cm(2).
Citation Count: 16
Applicability of Weyuker's Properties on OO Metrics: Some Misunderstandings
(Comsis Consortium, 2008) Misra, Sanjay; Akman, Ibrahim; Computer Engineering
Weyuker's properties have been suggested as a guiding tool in identification of a good and comprehensive complexity measure by several researchers. Weyuker proposed nine properties to evaluate complexity measure for traditional programming. However, they are extensively used for evaluating object-oriented (OO) metrics, although the object-oriented features are entirely different in nature. In this paper, two recently reported OO metrics were evaluated and, based on it; the usefulness and relevance of these properties for evaluation purpose for object-oriented systems is discussed.
Citation Count: 3
Application of FNBDT/SCIP protocol on local area network and determination of limit values;
(2010) Dilli,O.; Akçam,N.; Koyuncu,M.; Information Systems Engineering
Fast progress in technologies affects all the domains as well as the communication systems. Different types of systems or devices are developed and given to the services without losing time. Although these progresses, in general, have positive effects sometimes they may cause some problems. One of these problems is that the different terminal devices based on ISDN, PSTN and IP cannot communicate end-to-end with each other in a seamless secure way. In this study, FNBDT (Future Narrow Band Digital Terminal)/SCIP (Secure Communication Interoperability Protocol) protocol, which is developed for end-to-end secure communication of different terminal devices communicating on different networks, is tested from different perspectives using terminal emulator on IP Networks. These types of study have great importance in terms of providing some feedbacks to the development of FNBDT/SCIP and, as one of the initial work on this topic, this study will contribute to the future works in the area.
Citation Count: 10
Application of rfid in aviation industry: An exploratory review
(Faculty of Transport and Traffic Engineering, 2010) Mishra,A.; Mishra,D.; Computer Engineering; Software Engineering
Recently, Radio Frequency Identification (RFID) has received considerable attention and is considered to be the next wave of information technology revolution. The number of RFID applications in different industries is increasing continuously. Cumulative sales of RFID tag is up in 2006 which shows RFID adoption trend in industries to improve their efficiency of operations and to gain a competitive advantage. In the aviation industry, major airports, airlines have been also planning the RFID adoption in baggage handling and customer services areas for a long time. Many pilot tests have been performed at various airports and RFID tags were found to be far more precise along with better performance than bar codes. This paper provides a review on RFID systems, associated technology, advantages, limitations and applications in various fields. Further, this paper reports the preliminary review of state of RFID adoption planning, architecture and implementation plan in a major airline, focusing on improved baggage handling, increased airport/airline security and customer services.
Citation Count: 0
An approach for performance prediction of saturated brushed permanent magnet\rdirect current (DC) motor from physical dimensions
(Tubitak Scientific & Technological Research Council Turkey, 2022) Asl, Rasul Tarvirdilu; Zeinali, Reza; Ertan, Hulusi Bulent; Electrical-Electronics Engineering
An analytical approach for performance prediction of saturated brushed permanent magnet direct current\r(DC) motors is proposed in this paper. In case of a heavy saturation in the stator back core of electrical machines, some\rflux completes its path through the surrounding air, and the conventional equivalent circuit cannot be used anymore.\rThis issue has not been addressed in the literature. The importance of considering the effect of the flux penetrating\rthe surrounding air is shown in this paper using finite element simulations and experimental results, and an analytical\rapproach is proposed to consider this effect on magnet operating point determination and performance prediction of\rsaturated brushed permanent magnet DC motors. An analytical method is also presented to determine the boundary\rradius of the surrounding air for obtaining accurate results in finite element (FE) solutions and analytical calculations.\rAn analytical approach based on Carter’s coefficient is also proposed to calculate the effective length of the magnet when\rthe length of the magnet and rotor length are not the same. The accuracy of the proposed analytical model is illustrated\rusing finite element simulations and experimental results. With this accuracy, this analytical model is very suitable to\rbe used for reliable and quick mathematical design optimization.
Citation Count: 0
As quiet as a mouse: Media use in Azerbaijan
(de Gruyter Mouton, 2020) Seyidov, Ilgar; Public Relations and Advertising
During the Soviet period, the media served as one of the main propagandist tools of the authoritarian regime, using a standardized and monotype media system across the Soviet Republics. After the collapse of the Soviet Union, 15 countries became independent. The transition from Soviet communism to capitalism has led to the reconstruction of economic, socio-cultural, and political systems. One of the most affected institutions in post-Soviet countries was the media. Media have played a supportive role during rough times, when there was, on the one hand, the struggle for liberation and sovereignty, and, on the other hand, the need for nation building. It has been almost 30 years since the Soviet Republics achieved independence, yet the media have not been freed from political control and continue to serve as ideological apparatuses of authoritarian regimes in post-Soviet countries. Freedom of speech and independent media are still under threat. The current study focuses on media use in Azerbaijan, one of the under-researched post-Soviet countries. The interviews for this study were conducted with 40 participants living in Nakhichevan and Baku. In-depth, semi-structured interview techniques were used as research method. Findings are discussed under six main themes in the conclusion.
Citation Count: 14
Assessing cognitive complexity in Java-based Object-Oriented systems: Metrics and tool support
(Slovak Academy of Sciences, 2016) Crasso,M.; Mateos,C.; Zunino,A.; Misra,S.; Polvorín,P.; Computer Engineering
Software cognitive complexity refers to how demanding the mental process of performing tasks such as coding, testing, debugging, or modifying source code is. Achieving low levels of cognitive complexity is crucial for ensuring high levels of software maintainability, which is one of the most rewardful software quality attributes. Therefore, in order to control and ensure software maintainability, it is first necessary to accurately quantify software cognitive complexity. In this line, this paper presents a software metric to assess cognitive complexity in Object-Oriented (OO) systems, and particularly those developed in the Java language, which is very popular among OO programming languages. The proposed metric is based on a characterization of basic control structures present in Java systems. Several algorithms to compute the metric and their materialization in the Eclipse IDE are also introduced. Finally, a theoretical validation of the metric against a framework specially designed to validate software complexity metrics is presented, and the applicability of the tool is shown by illustrating the metric in the context of ten real world Java projects and relevant metrics from the well-known Chidamber-Kemerer metric suite.
Citation Count: 12
Assessing team work in engineering projects
(Tempus Publications, 2015) Mishra,D.; Ostrovska,S.; Hacaloglu,T.; Mathematics; Computer Engineering; Information Systems Engineering
Team work is considered a valuable teaching technique in higher education. However, the assessment of an individual's work in teams has proved to be a challenging task. Consequently, self- and peer-evaluations are becoming increasingly popular for the assessment of individuals in a team work, though it is essential to determine whether students can judge their ownas well as their peer's performance effectively. Self- and peer-evaluations have been applied in different disciplines and their authenticity with regard to teacher's assessment has been evaluated in the literature but this issue has not been investigated in the field of engineering education so far. In this study, a peer- and self-assessment procedure is applied to the evaluation of a project work conducted in teams of 3 or 4 students. The participants were engineering students taking two similar courses related with database design and development. It is found that a majority of the students were unable to assess themselves as objectively as their instructor. Further, it is observed that successful students tend to under-estimate, whereas unsuccessful students tend to over-estimate, their own performance. The paper also establishes that the results of self-assessments are independent from the gender factor. © 2015 TEMPUS Publications.
Citation Count: 13
Assessing the Coverage of E-Health Services in Sub-Saharan Africa A Systematic Review and Analysis
(Georg Thieme verlag Kg, 2017) Adeloye, Davies; Adigun, Taiwo; Misra, Sanjay; Omoregbe, Nicholas; Computer Engineering
Background: E-Health has attracted growing interests globally. The relative lack of facilities, skills, funds and information on existing e-Health initiatives has affected progress on e-Health in Africa. Objectives: To review publicly available literature on e-Health in sub-Saharan Africa (sSA) towards providing information on existing and ongoing e-Health initiatives in the region. Methods: Searches of relevant literature were conducted on Medline, EMBASE and Global Health, with search dates set from 1990 to 2016. We included studies on e-Health initiatives (prototypes, designs, or completed projects) targeting population groups in sSA. Results: Our search returned 2322 hits, with 26 studies retained. Included studies were conducted in 14 countries across the four sub-regions in sSA (Central, East, South and West) and spreading over a 12-year period, 2002-2014. Six types of e-Health interventions were reported, with 17 studies (65%) based on telemedicine, followed by mHealth with 5 studies (19%). Other e-Health types include expert system, electronic medical records, e-mails, and online health module. Specific medical specialties covered include dermatology (19%), pathology (12%) and radiology (8%). Successes were 'widely reported' (representing 50% overall acceptance or positive feedbacks in a study) in 10 studies (38%). The prominent challenges reported were technical problems, poor inter net and connectivity, participants' selection biases, contextual issues, and lack of funds. Conclusion: E-Health is evolving in sSA, but with poorly published evidence. While we call for more quality research in the region, it is also important that population-wide policies and on-going e-Health initiatives are contextually feasible, acceptable, and sustainable.
Citation Count: 15
Assessment of Shock Models for a Particular Class of Intershock Time Distributions
(Springer, 2022) Kus, Coskun; Tuncel, Altan; Eryilmaz, Serkan; Industrial Engineering
In this paper, delta and extreme shock models and a mixed shock model which combines delta-shock and extreme shock models are studied. In particular, the interarrival times between successive shocks are assumed to belong to a class of matrix-exponential distributions which is larger than the class of phase-type distributions. The Laplace -Stieltjes transforms of the systems' lifetimes are obtained in a matrix form. Survival functions of the systems are approximated based on the Laplace-Stieltjes transforms. The results are applied for the reliability evaluation of a certain repairable system consisting of two components.

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