WoS

Permanent URI for this collectionhttps://hdl.handle.net/20.500.14411/18

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Citation - WoS: 5
Citation - Scopus: 5
2-D Digital Filter Realization Without Overflow Oscillations
(Pergamon-elsevier Science Ltd, 2013) Singh, Vimal; Department of Mechatronics Engineering; 01. Atılım University
A novel criterion for the elimination of overflow oscillations in 2-D state-space digital filters described by the Roesser model employing two's complement overflow arithmetic is presented. The criterion takes the form of linear matrix inequality (LMI) and, hence, is computationally tractable. The criterion is a generalization and improvement over an earlier criterion. An example shows the effectiveness of the new criterion. (C) 2012 Elsevier Ltd. All rights reserved.
Citation - WoS: 6
Citation - Scopus: 10
3-D Dynamic Uav Base Station Location Problem
(informs, 2021) Cicek, Cihan Tugrul; Shen, Zuo-Jun Max; Gultekin, Hakan; Tavli, Bulent; Industrial Engineering; 06. School Of Engineering; 01. Atılım University
We address a dynamic covering location problem of an unmanned aerial vehicle base station (UAV-BS), in which the location sequence of a single UAV-BS in a wireless communication network is determined to satisfy data demand arising from ground users. This problem is especially relevant in the context of smart grid and disaster relief. The vertical movement ability of the UAV-BS and nonconvex covering functions in wireless communication restrict utilizing classical planar covering location approaches. Therefore, we develop new formulations to this emerging problem for a finite time horizon to maximize the total coverage. In particular, we develop a mixed-integer nonlinear programming formulation that is nonconvex in nature and propose a Lagrangean decomposition algorithm (LDA) to solve this formulation. Because of the high complexity of the problem, the LDA is still unable to find good local solutions to large-scale problems. Therefore, we develop a continuum approximation (CA) model and show that CA would be a promising approach in terms of both computational time and solution accuracy. Our numerical study also shows that the CA model can be a remedy to build efficient initial solutions for exact solution algorithms. Summary of Contribution: This paper addresses a facet of mixed integer nonlinear programming formulations. Dynamic facility location problems (DFLPs) arise in a wide range of applications. However, classical DFLPs typically focus on the two-dimensional spaces. Emerging technologies in wireless communication and some other promising application areas, such as smart grids, have brought new location problems that cannot be solved with classical approaches. For practical reasons, many research attempts to solve this new problem, especially by researchers whose primary research area is not OR, have seemed far from analyzing the characteristics of the formulations. Rather, solution-oriented greedy heuristics have been proposed. This paper has two main objectives: (i) to close the gap between practical and theoretical sides of this new problem with the help of current knowledge that OR possesses to solve facility location problems and (ii) to support the findings with an exhaustive computational study to show how these findings can be applied to practice.
3-D Gravity Modeling of the Kars Basin as a Hidden Extension of the Caspian Petroleum System, Ne-Anatolia, Turkey
(Springer Basel Ag, 2024) Aydemir, Attila; Bilim, Funda; 01. Atılım University
The Kars Basin in northeastern Turkey is closely related to the Caspian Petroleum System but it is hidden by a great extent of volcanic rocks. The Oligo-Miocene Komurlu Formation within the basin is the Turkish equivalent of the Maikopian Formation which is the main source rock in the Caspian region. Although the Kars Basin has considerable hydrocarbon potential it is one of the least explored basins in Turkey and there is only a limited literature on the region. This study is the first comprehensive investigation to determine the basement geometry, depth, internal structure and basin boundaries. Gravity data and power spectrum analysis were used in this study. The gravity anomalies were low-pass filtered and the average depth of the basin is found to be approximately 5 km. Boundaries of the basin are entirely confined within the Turkish territorial borders. The basin geometry is remarkably consistent with the crustal thickness geometry across the region and the maximum crustal thickness is 42 km, indicating that the basin was formed on the thickest part of the crust in the region. A 3-D model of the Kars Plateau indicates that the Kars Basin is made up of four different deep (> 6 km) depressions forming a channel-like trend from southwest to northeast from the Horasan area to the Arpacay area. There are four less deep sections (< 6 km) to the north of this trend. The depressions in the north are separated by the Allahuekber Mountains that are marked by a distinctive magnetic anomaly, from the deep SW-NE trend. High-standing regions between the depressions could be prospective areas for the oil accumulation.
A Factory in a Time of Turmoil: The Establishment and Engineering of the Büyükdere Match Factory in 1930s Istanbul
(MDPI, 2025) Tunc, Gokhan; Tunc, Tanfer Emin; Civil Engineering; 06. School Of Engineering; 01. Atılım University
The Republic of Turkey established its first match factory in Sinop in 1929 but had to relocate it even before it was in operation due to severe structural damage caused by ground settlement. In July 1930, through his US-based firm the American-Turkish Investment Corporation (ATIC), the Swedish "Match King" Ivar Kreuger signed a contract with the Republic of Turkey to build and operate a factory in B & uuml;y & uuml;kdere, Istanbul. By 1930, Kreuger had already established a match production monopoly in nearly every country in Europe and that year created a similar financial system for Turkey, gaining control of match production for 25 years. This article explains the events surrounding the establishment of his modern production facility in Turkey, with a particular focus on its engineering aspects. It details the strategically chosen location, the engineering solutions for the factory's construction, its production lines, and what the country gained and lost from it. In order to determine the establishment and production processes of the facility, the authors examined domestic and foreign archival documents, firsthand news reports from the period, articles and theses, and all other available documents. After the contract was terminated by both parties, the Turkish government and ATIC, in May 1943, the factory continued its production and storage activities until May 1989. At that point, the factory and all its equipment were integrated into another existing facility in the & Idot;neg & ouml;l district of Bursa province. Almost all the buildings of the B & uuml;y & uuml;kdere Match Factory were demolished, and the land was repurposed for a 450-bed regional hospital in 2012. In short, this article deploys the B & uuml;y & uuml;kdere Match Factory as a case study to examine what Turkey gained and lost from the establishment and production processes of a modern industrial factory, enabled by US-Turkish collaboration, and equipped with the most advanced manufacturing and engineering technologies of the time.
A New Conservative Numerical Method for Strongly Coupled Nonlinear Schrödinger Equations
(Springer Heidelberg, 2025) Ors, Ridvan Fatih; Koroglu, Canan; Aydin, Ayhan; Mathematics; 02. School of Arts and Sciences; 01. Atılım University
In this paper, a numerical method based on the conservative finite difference scheme is constructed to numerically solve the strongly coupled nonlinear Schr & ouml;dinger (SCNLS) equation. Conservative properties such as energy and mass of the SCNLS equation have been proven. In particular a fourth-order central difference scheme is used to discretize the the spatial derivative and a second-order Crank-Nicolson type discretization is used to discretize the temporal derivative. It has been shown that the proposed scheme preserves the discrete mass and energy. The existence of discrete solution is also investigated. Several numerical results are given to demonstrate the preservation properties of the new method. Also, the effect of the linear coupling parameters on the evolution of solitary waves is investigated.
Citation - WoS: 31
Citation - Scopus: 41
Accessibility Evaluation of Top University Websites: a Comparative Study of Kyrgyzstan, Azerbaijan, Kazakhstan and Turkey
(Springer Heidelberg, 2018) Ismailova, Rita; Inal, Yavuz; Information Systems Engineering; 06. School Of Engineering; 01. Atılım University
It is important that university websites and services offered through their sites are used effectively, efficiently and satisfactorily by the whole target group of the university, including disabled users. However, universities in many countries are still unable to meet the criteria for web accessibility. This study aimed to test the websites of the top universities in Kyrgyzstan, Kazakhstan, Azerbaijan and Turkey using automated assessment tools. The results showed that university websites are more popular in Turkey, and in Turkish universities developers pay more attention to the performance of websites, followed by websites of Azerbaijani, Kyrgyz and Kazakh universities. The majority of the university websites in the study did not meet the WCAG 2.0 accessibility criteria. Only two Kyrgyz and two Kazakh university websites attained conformance level A, and only three, one Kyrgyz and two Kazakh, achieved accessibility conformance level AAA. Based on the results, it was determined that universities included in the present study need to devote more effort to making their websites more accessible for their users.
Citation - WoS: 13
Citation - Scopus: 14
Activation Energy of Metastable Amorphous Ge₂sb_{2< 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; 15. Graduate School of Natural and Applied Sciences; 01. Atılım University
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 - WoS: 4
Citation - Scopus: 4
Adaptation of Food Craving Inventory To Turkish Culture: a Validity and Reliability Study
(Bmc, 2022) Ozel, Irem Cagla; Yabanci Ayhan, Nurcan; Cetiner, Ozlem; Nutrition and Dietetics; 07. School of Health Sciences; 01. Atılım University
Plain English Summary This study was carried out to adapt the Food Craving Inventory to Turkish. The English version of inventory consists of 4 sub-factors that measure cravings for high-fat foods, carbohydrates/starches, sweets, and fast food fats, and creates a total score. The sample of the study consists of 621 individuals between the ages of 19-50 who voluntarily agree to participate in an online survey. This study revealed that FCI-TR is a valid instrument of specific food cravings in the Turkish adult population. Turkish version of the FCI also consist of 4 sub-factors. Women experienced more food craving for sweets than men. While the most craved food by women was chocolate, men scored significantly higher on bread than women. In addition, a relationship was found between food craving and body weight. Introduction The Food Craving Inventory is a 28-item self-report measure of specific food cravings. The inventory consists of 4 factors: high fats, sweets, carbohydrates/starches and fast-food fats. Purpose This study was carried out to evaluate the Turkish validity and reliability of the Food Craving Inventory, and to determine the psychometric properties and factor structure of the Turkish version. Methods The sample of the study consists of 621 individuals between the ages of 19-50 who voluntarily agree to participate in online survey. Validity and reliability analyses were performed for the Turkish version of Food Craving Inventory (FCI-TR). Confirmatory factor analysis was performed to evaluate the factor structure of the Turkish version of FCI. Results Confirmatory factor analysis yielded a four-factor structure as "sweets," "high-fats," "carbohydrates/starches" and "fast food fats". The Cronbach-alpha coefficient for the total score was 0.84; subfactors were calculated as 0.74 for "sweets", 0.64 for "high-fat foods", 0.65 for "carbohydrates/starches", and 0.66 for "fast-food fats". The scores of the FCI-TR factors and its total score significantly correlated with the sub-factors of Three Factor Eating Questionnaire (TFEQ). A significant correlation was found between body mass index (BMI) and high fats and fast-food fats factor score. Also total and factor scores of the FCI-TR were different between BMI groups. Conclusions This study demonstrates that the Turkish version of the FCI is a valid and reliable tool to measure food cravings in the Turkish population. FCI is also correlated with sub-factors of TFEQ.
Citation - Scopus: 1
Adaptive Neuro-Fuzzy Inference Technique for Estimation of Light Penetration in Reservoirs
(Springer Japan Kk, 2007) Soyupak, Selcuk; Karaer, Feza; Senturk, Engin; Hekim, Huseyin; 01. Atılım University
An adaptive neuro-fuzzy inference technique has been adopted to estimate light levels in a reservoir. The data were collected randomly from Doganci Dam Reservoir over a number of years. The input data set is a matrix with vectors of time, depth, sampling location, and incident solar radiation. The output data set is a vector representing light measured at various depths. Randomization and logarithmic transformations have been applied as preprocessing. One-half of the data have been utilized for training; testing and validation steps utilized one-fourth each. An adaptive neuro-fuzzy inference system (ANFIS) has been built as a prediction model for light penetration. Very high correlation values between predictions and real values on light measurements with relatively low root mean square error values have been obtained for training, test, and validation data sets. Elimination of the overtraining problem was ensured by satisfying close root mean square error values for all sets.
Advances on Multivalued Operators and Related Fixed Point Problems
(Hindawi Publishing Corporation, 2014) Chen, Chi-Ming; Karapinar, Erdal; Du, Wei-Shih; Aydi, Hassen; Romaguera, Salvador; Mathematics; 02. School of Arts and Sciences; 01. Atılım University
[No Abstract Available]
Citation - WoS: 2
Citation - Scopus: 2
Advancing Mmwave Altimetry for Unmanned Aerial Systems: a Signal Processing Framework for Optimized Waveform Design
(Mdpi, 2024) Awan, Maaz Ali; Dalveren, Yaser; Kara, Ali; Derawi, Mohammad; Department of Electrical & Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 01. Atılım University
This research advances millimeter-wave (mmWave) altimetry for unmanned aerial systems (UASs) by optimizing performance metrics within the constraints of inexpensive automotive radars. Leveraging the software-defined architecture, this study encompasses the intricacies of frequency modulated continuous waveform (FMCW) design for three distinct stages of UAS flight: cruise, landing approach, and touchdown within a signal processing framework. Angle of arrival (AoA) estimation, traditionally employed in terrain mapping applications, is largely unexplored for UAS radar altimeters (RAs). Time-division multiplexing multiple input-multiple output (TDM-MIMO) is an efficient method for enhancing angular resolution without compromising the size, weight, and power (SWaP) characteristics. Accordingly, this work argues the potential of AoA estimation using TDM-MIMO to augment situational awareness in challenging landing scenarios. To this end, two corner cases comprising landing a small-sized drone on a platform in the middle of a water body are included. Likewise, for the touchdown stage, an improvised rendition of zoom fast Fourier transform (ZFFT) is investigated to achieve millimeter (mm)-level range accuracy. Aptly, it is proposed that a mm-level accurate RA may be exploited as a software redundancy for the critical weight-on-wheels (WoW) system in fixed-wing commercial UASs. Each stage is simulated as a radar scenario using the specifications of automotive radar operating in the 77-81 GHz band to optimize waveform design, setting the stage for field verification. This article addresses challenges arising from radial velocity due to UAS descent rates and terrain variation through theoretical and mathematical approaches for characterization and mandatory compensation. While constant false alarm rate (CFAR) algorithms have been reported for ground detection, a comparison of their variants within the scope UAS altimetry is limited. This study appraises popular CFAR variants to achieve optimized ground detection performance. The authors advocate for dedicated minimum operational performance standards (MOPS) for UAS RAs. Lastly, this body of work identifies potential challenges, proposes solutions, and outlines future research directions.
Citation - WoS: 8
Citation - Scopus: 9
Affective Experiences of the Parents of Children With Cancer: a Qualitative Study
(Springer, 2020) Demirtepe-Saygili, Dilek; Bozo, Ozlem; Department of Psychology; 02. School of Arts and Sciences; 01. Atılım University
The present study aims to examine the affective experiences of the parents of children with cancer qualitatively. Semi-structured interviews were conducted with parents, whose children were being treated for different types of childhood cancers. Three affect themes, which were (a) negative affect (sadness, anxiety guilt, and anger), (b) emotion suppression, and (c) positive affect were revealed as a result of the transcribed and qualitatively analyzed interviews. Theoretical explanations were provided for each theme. Negative affect was the most predominant theme, yet positive affect was also present among parents, and emotion suppression was an important part of the affective experiences. The findings offered a descriptive picture about the emotions of parents with respect to caregiving a child with cancer. It was suggested that normalization and ventilation of the emotions can help the parents cope better with childhood cancers.
Age replacement policies for discrete and continuous heterogeneous k-out-of-n systems
(Springer, 2024) Eryilmaz, Serkan; Bulanik, Irem; Industrial Engineering; 06. School Of Engineering; 01. Atılım University
This paper studies age replacement policy for the k-out-of-n system that consists of independent but nonidentical components. Both continuously and discretely distributed components' lifetimes are considered. The failed components are replaced by new components and non-failed components are rejuvenated. Because the components are non-identical, the acquisition and rejuvenation costs of the components are chosen differently. The policy and the associated optimization problem are presented for general k and n, and 2-out-of-3 systems are studied in detail. The findings of the present paper extend the results in the literature from parallel systems to k-out-of-n systems.
Citation - WoS: 25
Citation - Scopus: 36
Agile Project Management Tools: a Brief Comprative View
(inst information & Communication Technologies-bulgarian Acad Sciences, 2019) Ozkan, Deniz; Mishra, Alok; Software Engineering; 06. School Of Engineering; 01. Atılım University
Agile methodologies are becoming popular in software development. Managers are required to understand project's progress and product quality without development documents. During Agile practices of the teams and organizations, Agile project management tools are frequently used. The use of such tools leads to achieving speed and efficiency, affects the quality of the software. The quality of final product is mostly related with to project management. Accordingly, the paper provides brief comparative perspective about the popular project management tools for agile projects. 16 popular Agile project management tools have been presented helping agile developers to plan and manage their tasks in an efficient manner. Taiga, Axosoft, Agielan, Planbox are more appropriate for start-up projects. The most twitted and most appreciated tools are reported as Jira, Trello, and VersionOne. SpiraTeam by Inflectra and Pivotal Tracker are other pricing and popular agile tools, providing flexibility to Agile developers and increase collaboration among team members.
Citation - WoS: 45
Citation - Scopus: 45
An Ambipolar Low Band Gap Material Based on Bodipy and Edot
(Elsevier Science Bv, 2009) Algi, Fatih; Cihaner, Atilla; Chemical Engineering; 06. School Of Engineering; 01. Atılım University
A novel donor-acceptor type conducting polymer based on BODIPY dye as acceptor and EDOT units as donor parts is synthesized electrochemically. The unique combination of BODIPY and EDOT units provides an ambipolar (n- and p-doping processes) low band gap material (4). This is the first example of p-n junction in an organic pi-conjugated material where BODIPY unit is incorporated directly in the main chain. Furthermore, the polymer film exhibits electrochromic behavior upon p-doping: a color change from light violet (neutral) to indigo (oxidized). (C) 2009 Elsevier B.V. All rights reserved.
Citation - WoS: 33
Citation - Scopus: 34
An ambipolar neutral state green polymeric electrochromic
(Elsevier, 2009) Algi, Fatih; Cihaner, Atilla; Chemical Engineering; 06. School Of Engineering; 01. Atılım University
The synthesis and properties of highly stable neutral state green polymeric electrochromic, P1, which is based on 5,8-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-2,3-di(1H-pyrrol-2-yl)quinoxaline were highlighted. P1 exhibits three well-defined absorption bands with a narrow band gap (1.17 eV). The n- and p-doping (ambipolar) processes suggest that P1 is one of the most promising neutral state green polymers and it can be used in supercapacitors as either cathode or anode electrode material. Apart from the stability and the robustness of the polymer film, P1 shows multi-electrochromic behavior; gray-purple in the reduced form and highly transmissive blue color in the oxidized state. (C) 2009 Elsevier B.V. All rights reserved.
Citation - WoS: 80
Citation - Scopus: 81
Amine Grafted Silica Supported Craupd Alloy Nanoparticles: Superb Heterogeneous Catalysts for the Room Temperature Dehydrogenation of Formic Acid
(Royal Soc Chemistry, 2015) Yurderi, Mehmet; Bulut, Ahmet; Caner, Nurdan; Celebi, Metin; Kaya, Murat; Zahmakiran, Mehmet; Chemical Engineering; 06. School Of Engineering; 01. Atılım University
Herein we show that a previously unappreciated combination of CrAuPd alloy nanoparticles and amine-grafted silica support facilitates the liberation of CO-free H-2 from dehydrogenation of formic acid with record activity in the absence of any additives at room temperature. Furthermore, their excellent catalytic stability makes them isolable and reusable heterogeneous catalysts in the formic acid dehydrogenation.
Citation - WoS: 10
Citation - Scopus: 13
Analysing the Effects of Critique Techniques on the Success of Interior Architecture Students
(Wiley, 2018) Gul, Ciler Gozde Gunday; Afacan, Yasemin; 01. Atılım University
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 - WoS: 17
Citation - Scopus: 30
Analysis of Cultural and Gender Influences on Teamwork Performance for Software Requirements Analysis in Multinational Environments
(Wiley, 2012) Fernandez-Sanz, L.; Misra, Sanjay; Computer Engineering; 06. School Of Engineering; 01. Atılım University
Software development is mainly a social activity where teams of developers should work as a coordinated unit to fulfill the needs of customers. Studies have shown the importance of teamwork ability as the main skill for software professionals both in local settings and in global software development. Teamwork performance can be evaluated according to different approaches but we need deeper analysis within software teams of differences in individuals' performance related to culture, nationality or even gender. We applied a simple evaluation experience named teamwork benefits awareness (TBA) to groups of last-year students of computing degrees with experience as junior IT professionals during intensive multinational workshops based on international software projects. TBA allowed to measure individual and team performance during a requirements analysis session based on a real project. Results segmented by nationality and gender are presented and analysed in comparison with the data collected from computing professionals in local settings. In general, no significant differences have been found out although interesting relations are suggested with two Hofstede's country indicators. TBA is also perceived as a good technique for highlighting both teamwork benefits as well as the nature of real situations of software requirements analysis and orientation to customer needs.
Citation - WoS: 12
Citation - Scopus: 12
Analysis of Non-Isothermal Warm Deep Drawing of Dual-Phase Dp600 Steel
(Springer France, 2019) Pepelnjak, T.; Kayhan, E.; Kaftanoglu, B.; Airframe and Powerplant Maintenance; Manufacturing Engineering; 06. School Of Engineering; 13. School of Civil Aviation (4-Year); 01. Atılım University
Improving the formability of the material is a key issue in the deep drawing process. Heating the material above its recrystallization temperature drastically increases formability, but in the case of dual phase (DP) steels, it results in a loss of their mechanical properties. To improve the drawing ratio, only the heating of the flange region in the warm temperature range up to 573K was studied on DP600 sheet steel by numerical simulation. A thermo-elastic-plastic finite element method (FEM) analysis of deep drawing at several drawing ratios was performed and compared with experimental results. During the experiments, the flange area of the blank was heated by induction heating, and the central part over the punch was cooled with spray water. Experimental results showed that limiting drawing ratio could be increased by 25.58%. The microstructure of the DP 600 steel was analyzed before and after the warm forming process. No significant changes were observed, and the high strength properties of the DP 600 steel remained intact. There was good agreement between numerical and experimental results.

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