Bilgisayar Mühendisliği Bölümü

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Citation - WoS: 2
Citation - Scopus: 2
Guest Editorial: Gamification and Persuasive Games for Software Engineering
(inst Engineering Technology-iet, 2019) O'Connor, Rory V.; Colomo-Palacios, Ricardo; Clarke, Paul; Yilmaz, Murat
Citation - WoS: 24
Citation - Scopus: 27
Partially Coherent Airy Beam and Its Propagation in Turbulent Media
(Springer Heidelberg, 2013) Sermutlu, Emre; Eyyuboglu, Halil T.
The properties of partially coherent Airy beam propagating in turbulent media are investigated. Firstly the variations in the intensity profile and the location of the Airy beam peak with respect to dislocation and width parameters are examined. On the source plane, it is shown that there is a threshold value of the dislocation parameter which determines whether the beam peak will lie on the negative or positive side of the axis. The changes in source beam power and source beam size with respect to dislocation and width parameters are also examined. Then analysis is made for partially coherent Airy beam propagating in turbulence against variations in propagation distance, dislocation and width parameters, structure constant and partial coherence. It is found that the peak of the Airy beam will always shift to the right for increasing propagation distance. But this shift will become less as the dislocation and width parameters are increased. Finally it is shown that higher levels of turbulence and partial coherence will lead to more spreading and shift the beam peak more toward the on-axis position.
Citation - WoS: 24
Citation - Scopus: 28
Interactive Three-Dimensional Virtual Environment To Reduce the Public Speaking Anxiety Levels of Novice Software Engineers
(inst Engineering Technology-iet, 2019) Yilmaz, M.; Gulec, U.; Yilmaz, A. E.; Isler, V.; O'Connor, R. V.; Clarke, P.; Nazligul, M. Denizci
Software engineering is a set of activities that rely not only on the technical tasks but also require abilities focused on social duties such as daily meetings and product introduction presentations. However, engineers may experience elevated levels of anxiety when required to present their work in an unfamiliar environment. More specifically, they may suffer from public speaking anxiety even though they are supposed to be effective in those social tasks as well as in their engineering activities. Fortunately, previous studies suggest that the virtual exposure intervention is an effective strategy to reduce public speaking anxiety. In this study, an interactive three-dimensional virtual environment similar to real classrooms and auditoriums was developed to examine whether this might decrease the anxiety levels of novice software engineers. To compare the traditional and virtual exposure intervention, the sample set was divided equally into two groups including one experimental group and one control group. For 4 weeks, the virtual exposure intervention was conducted in the experimental group, whereas the cognitive behaviour therapy-based psychoeducation was used in the control group. The findings from authors' study illustrate that the virtual exposure intervention may represent an alternative solution to the traditional interventions for software engineers seeking to overcome public presentation anxiety.
Citation - WoS: 8
Citation - Scopus: 7
Sputtering Yield and Dynamical Analysis of Ni(100) Surface: a Comparison of Four Different Ar-Surface Interaction Potentials
(Elsevier Science Bv, 2000) Güvenç, ZB; Hundur, Y; Hippler, R
The sputtering process of the Ar + Ni(100) collision system is investigated by means of constant energy molecular dynamics simulations. The Ni(100) is mimicked by an embedded-atom potential, and the interaction between the projectile and the surface is modelled by using four different screened Coulomb type potentials. The Ni atom emission from the lattice is analysed over the range of 10-40 eV collision energy. The maximum penetration depths of Ar, probability distributions of kinetic energy of the reflected Ar, and energy of the Ar and sputtered Ni atoms in the same collision events are evaluated as functions of the impact energy and sputtering time. Further, angular distributions of the scattered Ar are obtained. The calculated sputtering yields are compared with the available theoretical and experimental data. (C) 2000 Elsevier Science B.V. All rights reserved.
Citation - WoS: 2
Citation - Scopus: 6
Understanding Personality Differences in Software Organisations Using Keirsey Temperament Sorter
(inst Engineering Technology-iet, 2015) O'Connor, Rory V.; Yilmaz, Murat
In recent years, there has been an increasing interest in exploring personality differences to improve work experience in software organisations. This study presents a personality assessment process conducted on 382 software practitioners using the Keirsey temperament sorter II. The primary goal of this assessment is to explore the personality temperaments of software practitioners working in different types of software development organisations. In addition, a novel visualisation approach is proposed for arranging temperaments using a periodic table-like structure. The results suggest that the authors approach provides an effective means to investigate an organisation's personality profile while assessing personality types.
Citation - WoS: 158
The Unusually Stable B100 Fullerene, Structural Transitions in Boron Nanostructures, and a Comparative Study of Α- and Γ-Boron and Sheets
(Amer Chemical Soc, 2010) Mukhopadhyay, S.; Hayami, W.; Guvenc, Z. B.; Pandey, R.; Boustani, I.; Ozdogan, C.
Solid alpha-B-12 rhombohedral and gamma-B-28 orthorhombic boron as well as boron nanostructures in the form of spheres, sheets, and multirings beside a ring consisting of icosahedral B-12 units were investigated using ab initio quantum chemical and density functional methods. The structure of the 131(x) fullerene exhibits unusual stability among all noninteracting free-standing Clusters, and is more stable than the 13120 cluster fragment of the gamma-B-28 solid, recently predicted and observed by Oganov et al. (Nature 2009, 457, 863). In addition, we compared the stability of the multirings and reported the structural transition from double-ring to triple-ring systems. This structural transition Occurs between B-52 and B-54 Clusters. We confirm that the noninteracting free-standing triangular buckled-sheet is more stable than the gamma-sheet, assembled in this work, and than the a-sheet, proposed by Tang and Ismail-Beigi (Phys. Rev. Lett. 2007, 99, 115501). In contrast, however, when these sheets are considered as infinite periodic systems, then the a-sheet remains the most stable one.
Citation - WoS: 107
Citation - Scopus: 111
Determination of Complete Melting and Surface Premelting Points of Silver Nanoparticles by Molecular Dynamics Simulation
(Amer Chemical Soc, 2013) Yavuz, M.; Zhou, Y.; Alarifi, H. A.; Atis, M.; Ozdogan, C.; Hu, A.
A molecular dynamics simulation based on the embedded-atom method was conducted at different sizes of single-crystal Ag nanoparticles (NPs) with diameters of 4 to 20 nm to find complete melting and surface premelting points. Unlike the previous theoretical models, our model can predict both complete melting and surface premelting points for a wider size range of NPs. Programmed heating at an equal rate was applied to all sizes of NPs. Melting kinetics showed three different trends that are, respectively, associated with NPs in the size ranges of 4 to 7 rim, 8 to 10 nm, and 12 to 20 nm. NPs in the first range melted at a single temperature without passing through a surface premelting stage. Melting of the second range started by forming a quasi-liquid layer that expanded to the core, followed by the formation of a liquid layer of 1.8 nm thickness that also subsequently expanded to the core with increasing temperature and completed the melting process. For particles in the third range, the 1.8 nm liquid layer was formed once the thickness of the quasi-liquid layer reached S rim. The liquid layer expanded to the core and formed thicker stable liquid layers as the temperature increased toward the complete melting point. The ratio of the quasi-liquid layer thickness to the NP radius showed a linear relationship with temperature.
Citation - WoS: 12
Citation - Scopus: 14
Reactions of Small Ni Clusters With a Diatomic Molecule: Md Simulation of D2+nin (n=7-10) Systems
(Elsevier Science Bv, 2000) Durmus, P; Böyükata, M; Özçelik, S; Güvenç, ZB; Jellinek, J
The kinetics of the reactions of nickel clusters with a deuterium molecule are studied, Dissociative chemisorption probabilities of the D(2) molecule on the small Ni(n) (n=7-10) clusters are computed by a quasi-classical molecular dynamics computer simulation technique. Structures of the clusters are obtained by an embedded-atom potential, and the interaction between the D(2) and Ni(n) is modelled by an LEPS (London-Eyring-Polanyi-Sato) function (energy surface). This analysis includes the chemisorption probabilities as functions of the impact parameter and of the relative translational energy of the D(2). The corresponding reactive cross-sections for the ground state of the molecule are calculated as functions of the collision energy and the size of the cluster. The role of the size of the clusters is examined. An indirect mechanism to the reaction, which involves formation of molecular adsorption as precursors to dissociative adsorption in the low collision energy region (less than 0.1eV), is observed. Results are discussed by comparing with the other similar theoretical and experimental studies. (C) 2000 Elsevier Science B.V. All rights reserved.
Citation - WoS: 17
Citation - Scopus: 18
Boron Doped Graphene Nanostructures
(Wiley-v C H verlag Gmbh, 2008) Ozdogan, Cem; Kunstmann, Jens; Fehske, Holger; Quandt, Alexander
We present results from an ab initio study of metallized semiconducting graphene nanostructures. Our model system consists of an alternating chain of quasi-planar B-7 clusters embedded into a semiconducting arm-chair nanoribbon. We observe the appearance of overlapping bands around the Fermi-level, with crystal momenta pointing into the direction of these boron chains. This observation could be a vantage point for the development of graphene nanodevices and integrated nanocircuits, based on existing technologies. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Citation - WoS: 13
Citation - Scopus: 17
Integration of Accessibility Design Patterns With the Software Implementation Process of Iso/Iec 29110
(Wiley, 2019) Sanchez-Gordon, Mary; Yilmaz, Murat; O'Connor, Rory V.; Sanchez-Gordon, Sandra
The Web Content Accessibility Guidelines was developed by World Wide Web Consortium with a goal of providing a single shared standard for web content accessibility that meets the needs of individuals, organizations, and governments. Given that there is a large percentage of very small entities that develop software who also utilize the ISO/IEC software process standard, the purpose of this study is the development of software design patterns for users with visual disabilities. As a result, four accessibility design patterns are defined: Authentication adapter, Blindness adapter, Dichromatic color vision adapter, and Blurry vision adapter. These patterns will help to improve the design of the web applications built using them while being compliant with the ISO/IEC 29110 standard. The use of design patterns also enables the transfer of design experience to programming practices and improves the software documentation. To validate the set of patterns, an online course for Spanish speakers was developed, and the evaluation was carried out using simulators, automated tools, experts, and users. Simulators and automated tools showed no accessibility errors and experts evaluated 10 heuristics principles and did not identify any severity issues. Taken together, our results provide positive evidence that users with visual disabilities could benefit from the proposed features.
Citation - WoS: 3
Citation - Scopus: 4
Improving Social Aspects of the Software Development Process: Games, Gamification and Related Approaches
(Graz Univ Technolgoy, inst information Systems Computer Media-iicm, 2016) Yilmaz, Murat; Yılmaz, Murat; O'Connor, Rory V.; Mora, Manuel; Yazılım Mühendisliği
Surface modification by 1 keV ion impact: molecular dynamics study of an Ar+-Ni(100) collision system
(2008) Özdoğan, Cem; Atis, Murat; Güvenç, Ziya B.
An Ar+-Ni(1 0 0) collision system at 1 keV impact energy was investigated by using realistic isoenergetic molecular dynamics (MD) simulations. The sputtering process upon Ar+ ion impact and damage to the Ni(1 0 0) surface are examined in detail. Studying of high bombarding energy regions leads to the necessity of larger and thick enough slabs, otherwise incoming ions can easily pass through the slab; as a result, investigated physical properties may not be revealed. In addition the simulation time should be long enough to observe and to calculate a reliable macroscopic property such as sputtering yield that is addressed in this study. In order to preserve the total energy in the simulation at this collision energy a small time-step (0.1 fs) is used. We have made use of our developed linear scaling parallel MD program to overcome these demands. The Ni(1 0 0) slab is formed by 63700 atoms (122 angstrom x 122 angstrom x 44 angstrom) and the total observation time for each collision event is about 2.25 ps. Several properties such as penetration depths, angular and energy distributions of the reflected Ar and sputtered Ni atoms as well as dissociation time, embedded, scattering, sputtering patterns and geometries of the sputtered clusters are also reported, and the calculated sputtering yield is found to be in good agreement with the available experimental results.
The impact of feature types, classifiers, and data balancing techniques on software vulnerability prediction models
(2019) Kaya, Aydın; Keçeli, Ali Seydi; Çatal, Çağatay; Tekinerdoğan, Bedir
Software vulnerabilities form an increasing security risk for software systems, that might be exploited to attack and harm the system. Some of the security vulnerabilities can be detected by static analysis tools and penetration testing, but usually, these suffer from relatively high false positive rates. Software vulnerability prediction (SVP) models can be used to categorize software components into vulnerable and neutral components before the software testing phase and likewise increase the efficiency and effectiveness of the overall verification process. The performance of a vulnerability prediction model is usually affected by the adopted classification algorithm, the adopted features, and data balancing approaches. In this study, we empirically investigate the effect of these factors on the performance of SVP models. Our experiments consist of four data balancing methods, seven classification algorithms, and three feature types. The experimental results show that data balancing methods are effective for highly unbalanced datasets, text-based features are more useful, and ensemble-based classifiers provide mostly better results. For smaller datasets, Random Forest algorithm provides the best performance and for the larger datasets, RusboostTree achieves better performance.
Citation - WoS: 11
Citation - Scopus: 13
The Diagnosis of Developmental Dysplasia of the Hip From Hip Ultrasonography Images With Deep Learning Methods
(Lippincott Williams & Wilkins, 2023) Ureten, Kemal; Tokdemir, Gul; Tolunay, Tolga; Ciceklidag, Murat; Atik, Osman Sahap; Atalar, Hakan
Background:Hip ultrasonography is very important in the early diagnosis of developmental dysplasia of the hip. The application of deep learning-based medical image analysis to computer-aided diagnosis has the potential to provide decision-making support to clinicians and improve the accuracy and efficiency of various diagnostic and treatment processes. This has encouraged new research and development efforts in computer-aided diagnosis. The aim of this study was to evaluate hip sonograms using computer-assisted deep-learning methods. Methods:The study included 376 sonograms evaluated as normal according to the Graf method, 541 images with dysplasia and 365 images with incorrect probe position. To classify the developmental hip dysplasia ultrasound images, transfer learning was applied with pretrained VGG-16, ResNet-101, MobileNetV2 and GoogLeNet networks. The performances of the networks were evaluated with the performance parameters of accuracy, sensitivity, specificity, precision, F1 score, and AUC (area under the ROC curve). Results:The accuracy, sensitivity, specificity, precision, F1 score, and AUC results obtained by testing the VGG-16, ResNet-101, MobileNetV2, and GoogLeNet models showed performance >80%. With the pretrained VGG-19 model, 93%, 93.5%, 96.7%, 92.3%, 92.6%, and 0.99 accuracy, sensitivity, specificity, precision, F1 score, and AUC results were obtained, respectively. Conclusion:In this study, in addition to the ultrasonography images of dysplastic and healthy hips, images were also included of probe malpositioning, and these images were able to be successfully evaluated with deep learning methods. On the sonograms, which provided criteria appropriate for evaluation, successful differentiation could be made of healthy hips and dysplastic hips.
Citation - WoS: 7
Citation - Scopus: 8
Fragmentation of Water Clusters: Molecular-Dynamics Simulation Study
(Springer-verlag, 2001) Erkoç, S; Kökten, H; Güvenç, Z
The fragmentation of water clusters, [(H2O)(n): n = 2-8], have been investigated by using molecular-dynamics simulation method. In the simulations a polarizable-dissociable potential energy function for water has been used. Particular attention has been paid to investigate the effect of structural properties and cluster size of the fragmentation.
Citation - WoS: 49
Citation - Scopus: 49
Global Minima of Aln, Aun and Ptn, N≤80, Clusters Described by the Voter-Chen Version of Embedded-Atom Potentials
(Iop Publishing Ltd, 2005) Sebetci, A; Güvenç, ZB
We report the global minima for aluminium, gold and platinum metal clusters modelled by the Voter-Chen version of the embedded-atom model potential containing up to 80 atoms using the basin-hopping Monte Carlo minimization approach. The results show that the global minima of the Al, Au and Pt clusters have structures based on either octahedral, decahedral, icosahedral or a mixture of decahedral and icosahedral packing. The 54-atom icosahedron without a central atom is found to be more stable than the 55-atom complete icosahedron for all of the elements considered in this work. Most of the Al global minima are identified as face-centred cubic structures and many of the An global minima are found to be low symmetric structures, both of which are in agreement with the previous theoretical and experimental Studies. Although many of the Pt global minima are identical with the global minima of the corresponding Au clusters, the most stable sizes of the Pt clusters correspond to the same sizes of the Al clusters.
Citation - WoS: 7
Citation - Scopus: 10
A Literature Survey: Is It Necessary To Develop a New Software Development Methodology for Virtual Reality Projects
(Graz Univ Technolgoy, inst information Systems Computer Media-iicm, 2017) Güleç, Ulaş; Gulec, Ulas; Yilmaz, Murat; Yılmaz, Murat; Isler, Veysi; Bilgisayar Mühendisliği; Yazılım Mühendisliği
Software development is a complex human endeavour with high failure rates. Although a variety of software development methodologies have been proposed to improve the software development process, there is no universal model for all software development organizations. Virtual reality (VR) is an emerging trend especially for the gaming industry, which should prepare itself for VR development. The goal of this study is to explore potential software development activities and determine whether designing a new software development methodology for VR projects is an important topic for software development organizations working on VR software development. For this purpose, a literature survey has been completed and 71 academic studies have been examined in detail. This study shows that no work is being conducted in the field of developing a new methodology for VR projects. However, the study does show that there are similar endeavours in the field of human computer interaction (HCI), such as game development methodology.
Citation - WoS: 43
Citation - Scopus: 53
Gamification as a Disruptive Factor in Software Process Improvement Initiatives
(Graz Univ Technolgoy, inst information Systems Computer Media-iicm, 2014) Herranz, Eduardo; Yılmaz, Murat; Colomo-Palacios, Ricardo; de Amescua Seco, Antonio; Yilmaz, Murat; Yazılım Mühendisliği
For any Software Process Improvement (SPI) initiative to succeed human factors, in particular, motivation and commitment of the people involved should be kept in mind. In fact, Organizational Change Management (OCM) has been identified as an essential knowledge area for any SPI initiative. However, enough attention is still not given to the human factors and therefore, the high degree of failures in the SPI initiatives is directly linked to a lack of commitment and motivation. Gamification discipline allows us to define mechanisms that drive people's motivation and commitment towards the development of tasks in order to encourage and accelerate the acceptance of an SPI initiative. In this paper, a gamification framework oriented to both organization needs and software practitioners groups involved in an SPI initiative is defined. This framework tries to take advantage of the transverse nature of gamification in order to apply its Critical Success Factors (CSF) to the organizational change management of an SPI. Gamification framework guidelines have been validated by some qualitative methods. Results show some limitations that threaten the reliability of this validation. These require further empirical validation of a software organization.
Citation - WoS: 3
Observed Effects of Software Processes Change in Three Software Firms: Industrial Exploratory Case Study
(Pamukkale Univ, 2019) Yilmaz, Murat
Software development processes require continuous improvement in line with emerging new technologies and the possibilities it provides. A new generation of software development models based on product demands of software customers with marketable functions aims to increase the intermediate product production speed and thus the number of interim versions. In the light of these needs, software companies need to oversee their development processes to meet their customers' needs. But more importantly, companies are forced to change their processes in line with innovative practices in order not to cut back on the software production line. In this article, the software development methods of the three companies that develop software are examined in detail by the case study method, and the process change activities are systematically detailed. In the light of the information obtained, the experiences of the three firms in the software development methods are questioned and the effects of these acquisitions on the processes are discussed. As a result of the study, it has been observed that the software development success has a significant impact on the well-being of the process, and the software development teams are trying to design their own processes in the light of the gains they acquire.
Citation - WoS: 8
Citation - Scopus: 8
Localization of Metallicity and Magnetic Properties of Graphene and of Graphene Nanoribbons Doped With Boron Clusters
(Taylor & Francis Ltd, 2014) Kunstmann, Jens; Quandt, Alexander; Ozdogan, Cem
As a possible way of modifying the intrinsic properties of graphene, we study the doping of graphene by embedded boron clusters with density functional theory. Cluster doping is technologically relevant as the cluster implantation technique can be readily applied to graphene. We find that B-7 clusters embedded into graphene and graphene nanoribbons are structurally stable and locally metallize the system. This is done both by the reduction of the Fermi energy and by the introduction of boron states near the Fermi level. A linear chain of boron clusters forms a metallic "wire" inside the graphene matrix. In a zigzag edge graphene nanoribbon, the cluster-related states tend to hybridize with the edge and bulk states. The magnetism in boron-doped graphene systems is generally very weak. The presence of boron clusters weakens the edge magnetism in zigzag edge graphene nanoribbon, rather than making the system appropriate for spintronics. Thus, the doping of graphene with the cluster implantation technique might be a viable technique to locally metallize graphene without destroying its attractive bulk properties.

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