Mühendislik Fakültesi

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Citation - WoS: 0
Citation - Scopus: 2
A compact size multiband printed monopole antenna with triple sense circular polarization for wireless applications
(Natl inst Optoelectronics, 2020) Al-Mihrab, M.; Salim, A.; Al-Saedi, H.; Ali, J.
A penta-band printed monopole antenna based on a hexagonal open loop shape is presented in this paper. The proposed antenna demonstrated a variety in the polarization. Antenna is loaded with some parts and two stair-shaped slits is created in the partial ground plane for enhancing the multiband behavior. A circularly polarized (CP) waves are generated at a three bands with impedance bandwidths (IBWs) of 10.62%, 33.65% and 8.61% centered at 1.60, 5.20 and 6.50 GHz and 3-dB axial ratio bandwidths (ARBWs) of 9.10%, 7.58%, and 4.41% respectively. While a linearly polarized (LP) waves at the other two bands over ranges (2.51-2.64 GHz) and (3.10-3.31 GHz). Besides, the proposed antenna showed a different sense of circular polarization; right hand, left hand, and right hand. The antenna is simulated and fabricated on an FR-4 (glass epoxy) substrate with relative permittivity of 4.6, thickness of 1.6 mm and a loss tangent of 0.02. The properties of multiband and circular polarization, makes the proposed antenna candidates for many modern wireless applications.
Citation - Scopus: 0
A course flow model developed for software engineering course
(CEUR-WS, 2018) Yılmaz, M.; Güleç, U.
As in the rest of the world, many software projects in our country exceed the planned budget and time limits, and the user expectations are not fully met. One of the important reasons for this is the lack of work force that well-trained in software engineering domain. In this article, details of a course flow model and the results of the model for the CENG 396 Software Engineering course, which has been carried out in Çankaya University Department of Computer Engineering for the last four years, will be given. The aim of this study is to explain the lesson flow model which is designed to cultivate the appropriate software engineering and software engineers equipped to conditions in Turkey. In addition, the secondary aim is to share the results of the analysis of this study with other software engineer course instructors so that they can benefit from our experience and achievements.
Citation - WoS: 15
Citation - Scopus: 18
A Gamification Approach to Improve the Software Development Process by Exploring the Personality of Software Practitioners
(Springer-verlag Berlin, 2016) Yilmaz, Mert; Yılmaz, Murat; Yilmaz, Murat; O'Connor, Rory V.; Clarke, Paul; Yazılım Mühendisliği
Although there are various kinds of processes designed to manage the complexities of software development, it is still a challenging endeavor. Recently, a significant number of researchers have started to investigate social problems such as incompatibilities with respect to personality that is likely to be encountered in all stages of the software development process. However, there is no computer-based artifact to reveal the personality types of software practitioners. To bridge this gap, a virtual 3D assessment environment is developed with the ability to immerse individuals similar to a realistic model of the assessment. The interactive questionnaire is based on previous interactive personality assessment framework, which was specifically designed for software engineers. Based on the developed tool, a study was conducted on software practitioners. The data gathered via a survey study from software practitioners is analyzed to observe the difference between the results of paper-based and interactive versions of the same assessment. The analysis of this research states that there is a significant difference between the results of participant's survey scores. Overall, these results indicate that proposed tool is relevant to help software professionals to improve the software development process when personality types are in consideration.
Citation - Scopus: 6
A Machine-Based Personality Oriented Team Recommender for Software Development Organizations
(Springer Verlag, 2015) Yilmaz, M.; Yılmaz, Murat; Al-Taei, A.; O’Connor, R.V.; Yazılım Mühendisliği
Hiring the right person for the right job is always a challenging task in software development landscapes. To bridge this gap, software firms start using psychometric instruments for investigating the personality types of software practitioners. In our previous research, we have developed an MBTI-like instrument to reveal the personality types of software practitioners. This study aims to develop a personality-based team recommender mechanism to improve the effectiveness of software teams. The mechanism is based on predicting the possible patterns of teams using a machine-based classifier. The classifier is trained with empirical data (e.g. personality types, job roles), which was collected from 52 software practitioners working on five different software teams. 12 software practitioners were selected for the testing process who were recommended by the classifier to work for these teams. The preliminary results suggest that a personality-based team recommender system may provide an effective approach as compared with ad-hoc methods of team formation in software development organizations. Ultimately, the overall performance of the proposed classifier was 83.3%. These findings seem acceptable especially for tasks of suggestion where individuals might be able to fit in more than one team. © Springer International Publishing Switzerland 2015.
Citation - Scopus: 2
A Multiple Criteria Ranking Method Based on Outranking Relations: An Extension for Prospect Theory
(Springer Science and Business Media Deutschland GmbH, 2022) Karasakal, E.; Karasakal, Orhan; Karasakal, O.; Şentürk, H.; 216553; Endüstri Mühendisliği
In this study, Prospect Theory is integrated into a well-known multiple criteria ranking method, PROMETHEE. PROMETHEE considers the outranking relations among alternatives based on the preference functions. Prospect Theory evaluates the alternatives with a difference function based on gains and losses. The preference functions of PROMETHEE are modified to capture the choice behavior of the decision maker. The proposed method is a generalization of PROMETHEE that can handle the higher loss impact case as well as the usual equal loss and gain impact. The proposed method is compared with PROMETHEE, PT-PROMETHEE that is an extension of PROMETHEE with reference alternative, and the weighted sum method using an exemplary data set and Times Higher Education (THE) World University Ranking 2019 and 2020 data. The results show that rankings of alternatives change significantly when the impact of losses is larger than gains. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.
Citation - WoS: 0
A parametric study on the elastic-plastic deformation of a centrally heated two-layered composite cylinder with free ends
(Polish Acad Sciences inst Fundamental Technological Research, 2016) Yalcin, F.; Gülgeç, Müfit; Ozturk, A.; Gulgec, M.; 4168; Mekatronik Mühendisliği
In this paper, an elastic-plastic deformation of a centrally heated two-layered composite cylinder with free ends subjected to uniformly distributed internal energy generation within an inner cylinder is studied using Tresca's yield condition and its associated flow rule. Stress, strain and displacement distributions in the composite cylinder made of elastic-perfectly plastic material are derived considering the influence of geometric parameters as well as material properties such as yield strength, modulus of elasticity, Poisson's ratio, coefficient of thermal conduction and coefficient of thermal expansion. Yielding starts at the outer boundary or at the axis corresponding to an 'edge regime' of Tresca's prism in both cases. Propagations of the plastic regions are studied due to an increase of a heat generation.
Citation - Scopus: 0
A Study of the Structural and Mechanical Characterization of Hybrid Nanocomposite Material
(Trans Tech Publications Ltd, 2017) Mahmoud, A.K.; Demiral, Murat; Al-Nassar, S.I.; Demiral, M.; Kadhim, H.M.; Makine Mühendisliği
This work is devoted on the synthesized new hybrid nanocomposite materials by using mechanical stirring method through a combination of different types of material; epoxy based matrix and nanofiller (TiO2 nanoparticles) as a reinforcement material. In additional this paper studies the effect of TiO2 nanoparticles with percentage 2-8 wt% added to epoxy based matrix on the mechanical properties (tensile properties and hardness property). The results showed that the tensile strength of nanocomposite material increased gradually by increasing the weight percentage of TiO2 nanoparticles from 2 wt % to 8 wt % TiO2, while the best tensile strength was at 8 wt % TiO2. The maximum value of tensile strength was 270% higher than the neat epoxy matrix. The hardness increase gradually with increasing percentage of TiO2 nanoparticles from 2wt% TiO2 up to 8wt% TiO2, the maximum value of hardness was at 8wt % TiO2, so the hardness of nanocomposite is around 86% higher than the neat epoxy matrix. © 2017 Trans Tech Publications, Switzerland.
Citation - WoS: 12
Citation - Scopus: 17
A Systematic Investigation into the Use of Game Elements in the Context of Software Business Landscapes: A Systematic Literature Review
(Springer-verlag Berlin, 2017) Olgun, Serhan; Yılmaz, Murat; Yilmaz, Murat; Clarke, Paul M.; O'Connor, Rory V.; Yazılım Mühendisliği
The software development process is a set of socio-technical activities to produce software artifacts in which humans play a crucial role. Since it is a people centric activity, factors such as user motivation, engagement, communication and collaboration might constrain these activities. Therefore, software business organizations stand to benefit from adopting different tools and methods in order to overcome these obstacles and to improve their software business processes. Research has been made to increase software quality and enhance the software development process. Alongside these studies, innovative techniques and concepts are beneficial. As a solution, the notion of gamification (i.e. employing game elements in non-gaming contexts) has been introduced to enhance the software development process and overcome the challenges mostly related to human factors. However, the applicability of game elements in the context of software business landscapes is still a controversial issue and not totally proven as of yet. Numerous studies have been conducted to examine the benefits of gamification and how game elements affect the software development process. Thus, in this paper, a systematic literature review was conducted in order to investigate the application of game elements both in research and industrial levels of software development and as well as in software business landscapes.
Citation - WoS: 2
Citation - Scopus: 0
Adopting Augmented Reality for the Purpose of Software Development Process Training and Improvement: An Exploration
(Springer international Publishing Ag, 2018) Ohri, Ipek; Yılmaz, Murat; Oge, Irem; Orkun, Bora; Yilmaz, Murat; Tuzun, Eray; Clarke, Paul; O'Connor, Rory V.; Yazılım Mühendisliği
Augmented reality (AR) is a technological field of study that bridges the physical and digital world together with a view to improving user experience. AR holds great potential to change the delivery of software services or software process improvement by utilizing a specific set of components. The purpose of this exploratory study is to propose an integration framework to support AR for improving the onboarding process, notably in introducing new hires to the development process while performing their daily tasks. In addition, it also aims to enhance the software development workflow process using AR. Similar to a GPS device that can guide you from point A to point B, our goal is to create software artifacts like navigation components where software teams may benefit from digitally enhanced working conditions provided using AR. After conducting a review in the literature, we confirmed that there is lack of studies about the combination of augmented reality with software engineering disciplines for onboarding. In this paper, we formalized our approach based on the benefits of AR. Ultimately; we propose an AR-based preliminary model for improving the software development process.
Citation - WoS: 23
Citation - Scopus: 35
An exact solution procedure for multi-item two-echelon spare parts inventory control problem with batch ordering in the central warehouse
(Elsevier Science Bv, 2010) Topan, Engin; Topan, Engin; Bayindir, Z. Pelin; Tan, Tarkan; Endüstri Mühendisliği
We consider a multi-item two-echelon inventory system in which the central warehouse operates under a (Q, R) policy, and the local warehouses implement basestock policy. An exact solution procedure is proposed to find the inventory control policy parameters that minimize the system-wide inventory holding and fixed ordering cost subject to an aggregate mean response time constraint at each facility. (C) 2010 Elsevier B.V. All rights reserved.
Citation - Scopus: 6
An Exploration of Individual Personality Types in Software Development
(Springer Verlag, 2014) Yilmaz, M.; Yılmaz, Murat; O'Connor, R.V.; Clarke, P.; Yazılım Mühendisliği
Previous research - using conventional psychometric questionnaires - has highlighted the importance of aligning compatible personality types in software development teams. However, there does not exist a dedicated, robust questionnaire instrument for revealing the pertinent personality types for software development practitioners. This study analyzes the validity and reliability of a 70-item (context dependent) personality-profiling questionnaire particularly developed to assess personality types of software practitioners. A systematic process of validation, using an iterative approach to questionnaire development, was employed. The questions were developed both with a qualitative analysis of interview data, and based on the opinions of expert reviewers who revised the items through a set of examination. To investigate how stable the questions and reproducible the results, we measured test-retest reliability of the instrument, yielding satisfactory results. The present study provided evidence for the construct validity of the instrument. Ultimately, an initial comparison of the results delivered by the instrument demonstrated positive correlations with the findings acquired with well-known personality assessment instrument, i.e. the big five personality questionnaire. © Springer-Verlag Berlin Heidelberg 2014.
Citation - Scopus: 0
An industrial case study to improve the onboaring process in software management
(CEUR-WS, 2017) Yilmaz, M.; Güleç, U.; O'Connor, R.V.; Clarke, P.; Tüzün, E.
In this study, we investigate expert information about software process known to experienced software developers and study how this is to be transferred to the newly recruited software developers. By this means, the developers who are recruited to a software project should understand better the software development organization and especially its social structure more effectively. Through this work, along with structural and algorithmic improvements of the software product, problems related to adaptation to team culture, adaptation to company culture, and adaptation to software development tools used are also investigated. This study aims to find the requirements in the market so that the recruitment processes can be explored using serious game mechanics. With the help of an industrial case study, we question the applicability a serious game for recruitment in the industry by improving the on-boarding process which has been identified as a problem for many software companies.
Citation - WoS: 2
Citation - Scopus: 3
An intelligent system for detecting Mediterranean fruit fly
(Pagepress Publ, 2022) Uzun, Yusuf; Tolun, Mehmet Resit; Eyyuboglu, Halil Tanyer; Sari, Filiz
Nowadays, the most critical agriculture-related problem is the harm caused to fruit, vegetable, nut, and flower crops by harmful pests, particularly the Mediterranean fruit fly, Ceratitis capitata, named Medfly. Medfly's existence in agricultural fields must be monitored systematically for effective combat against it. Special traps are utilised in the field to catch Medflies which will reveal their presence and applying pesticides at the right time will help reduce their population. A technologically supported automated remote monitoring system should eliminate frequent site visits as a more economical solution. This paper develops a deep learning system that can detect Medfly images on a picture and count their numbers. A particular trap equipped with an integrated camera that can take photos of the sticky band where Medflies are caught daily is utilised. Obtained pictures are then transmitted by an electronic circuit containing a SIM card to the central server where the object detection algorithm runs. This study employs a faster region-based convolutional neural network (Faster R-CNN) model in identifying trapped Medflies. When Medflies or other insects stick on the trap's sticky band, they spend extraordinary effort trying to release themselves in a panic until they die. Therefore, their shape is badly distorted as their bodies, wings, and legs are buckled. The challenge is that the deep learning system should detect these Medflies of distorted shape with high accuracy. Therefore, it is crucial to utilise pictures containing trapped Medfly images with distorted shapes for training and validation. In this paper, the success rate in identifying Medflies when other insects are also present is approximately 94%, achieved by the deep learning system training process, owing to the considerable amount of purpose-specific photographic data. This rate may be seen as quite favourable when compared to the success rates provided in the literature.
Citation - WoS: 24
Citation - Scopus: 34
An Investigation of Software Development Process Terminology
(Springer-verlag Berlin, 2016) Clarke, Paul; Mesquida, Antoni-Lluis; Ekert, Damjan; Ekstrom, J. J.; Gornostaja, Tatjana; Jovanovic, Milos; Yilmaz, Murat
The practice of software development has evolved considerably in recent decades, with new programming technologies, the affordability of hardware, pervasive internet access and mobile computing all contributing to the emergence of new software development processes. The newer process initiatives, which include those which are sometimes referred to as agile or lean methods, have brought with them new terms, which sometimes reflect the introduction of novel concepts. Other times, new terms correspond to long established concepts that have been repackaged. The net position is that we have a proliferation of language and term usage in the software development process domain, a problem which has implications for assessors and assessment frameworks, and for the broader community. In this paper, we explore this problem, finding that it is worthy of further research. Plus, we identify a technique suited to addressing this concern: the establishment of a canonical software process ontological model.
Citation - Scopus: 0
Analog and digital filter design
(Springer Science and Business Media B.V., 2018) Gazi, O.; Gazi, Orhan; Elektronik ve Haberleşme Mühendisliği
In this chapter, we will study analog and digital filter design techniques. A filter is nothing but a linear time invariant (LTI) system. Any LTI system can be described using its impulse response. If the impulse response of a LTI system is known, then for any arbitrary input the system output can be calculated by taking the convolution of the impulse response and arbitrary input. This also means that filtering operation is nothing but a convolution operation. And filter design is nothing but finding the impulse response of a linear time invariant system. For this purpose, we can work either in time domain or frequency domain. © Springer Nature Singapore Pte Ltd. 2018.
Citation - WoS: 1
Citation - Scopus: 1
Analysıs Of Heat Transfer Enhancement In Tubes Wıth Capsule Dımpled Surfaces And Al2o3-Water Nanofluıd
(Turkish Soc thermal Sciences Technology, 2022) Yapici, Ekin Ozgirgin; Türkoğlu, Haşmet; Ibrahim, Mahmoud Awni A. Haj; Turkoglu, Hasmet; 31329; Makine Mühendisliği
This study aims to numerically investigate and evaluate the enhancement of heat transfer by new capsule dimples on tube surfaces for flow of water and Al2O3-water nanofluid with different concentrations, under uniform surface heat flux. The originality of this work lies in combining two passive heat transfer enhancement methods such as geometrical improvements and nanofluids together. Capsule dimples with different depths were considered. Al2O3- water nanofluid was modeled as a single-phase flow based on the mixture properties. The effects of dimple depth and nanoparticle concentrations on Nusselt number, friction factor and performance evaluation criteria (PEC) were studied. Numerical computations were performed using ANSYS Fluent commercial software for 2000-14000 Reynolds number range. It was found that when laminar, transient and fully developed turbulent flow cases are considered, increase in the dimple depth increases the Nusselt number and friction factor for both pure water and Al2O3-water nanofluids cases. Also, the friction factor increases as dimple depth increases. Results show that increase in PEC is more pronounced in the laminar region than in the transition region, it starts to decrease for turbulent flows. For nanofluid, PEC values are considerably higher than pure water cases. The variation of PEC for capsule dimpled tubes are dependent on flow regimes and dimple depths. Increasing the nano particle volume concentration and dimple depth in laminar flows increase the PEC significantly.
Citation - WoS: 0
Citation - Scopus: 1
Analysis of parallel decodable turbo codes
(Ieice-inst Electronics information Communications Eng, 2012) Gazi, Orhan; Gazi, Orhan; 102896; Elektronik ve Haberleşme Mühendisliği
Turbo codes suffer from high decoding latency which hinders their utilization in many communication systems. Parallel decodable turbo codes (PDTCs) are suitable for parallel decoding and hence have low latency. In this article, we analyze the worst case minimum distance of parallel decodable turbo codes with both S-random interleaver and memory collision free Row-Column S-random interleaver. The effect of minimum distance on code performance is determined through computer simulations.
Citation - WoS: 4
Citation - Scopus: 4
ANN and ANFIS Performance Prediction models for Francis type Turbines
(Turkish Soc thermal Sciences Technology, 2020) Ayli, Ece; Ulucak, Oguzhan; 265836
Turbines can be operated under partial loading conditions due to the seasonal precipitation fluctuations and due to the needed electrical demand over time. According to this partial working need, designers generate hill chart diagrams to observe the system behavior under different flow rates and head values. In order to generate a hill chart, several numerical or experimental studies have been performed at different guide vane openings and head values which are very time consuming and expensive. In this study, the efficiency prediction of Francis turbines has been performed with ANN and ANFIS methods under different operating conditions and compared with simulation results. The obtained results indicate that it is possible to obtain a hill chart using ANFIS method instead of a costly experimental or numerical tests. ANN and ANFIS parameters which effect the output, have been optimized with trying 100 different cases. 75% of the numerical data set is used for training and 25 % is used for validation as testing data. To asses and compare the performance of multiple ANN and ANFIS models several statistical indicators have been used. Insight to the performance evaluation, it is seen that ANFIS can predict the efficiency distribution with higher accuracy than the ANN model. The developed ANFIS model predicts the efficiency with 1.41% mean average percentage error and 0.999 R-2 value. To the best of the author's knowledge, this is the first study in the literature that ANN and ANFIS are used in order to predict the efficiency distribution of the turbines at different loading conditions.
Citation - WoS: 8
Citation - Scopus: 15
Applying Blockchain to Improve the Integrity of the Software Development Process
(Springer international Publishing Ag, 2019) Yılmaz, Murat; Yilmaz, Murat; Tasel, Serdar; Güleç, Ulaş; Tuzun, Eray; Gulec, Ulas; O'Connor, Rory V.; Clarke, Paul M.; 55346; Yazılım Mühendisliği; Bilgisayar Mühendisliği
Software development is a complex endeavor that encompasses application and implementation layers with functional (refers to what is done) and non-functional (how is done) aspects. The efforts to scale agile software development practices are not wholly able to address issues such as integrity, which is a crucial non-functional aspect of the software development process. However, if we consider most software failures are Byzantine failures (i.e., where components may fail and there is imperfect information on which a component has failed.) that might impair the operation but do not completely disable the production line. In this paper, we assume software practitioners who cause defects as Byzantine participants and claim that most software failures can be mitigated by viewing software development as the Byzantine Generals Problem. Consequently, we propose a test-driven incentive mechanism based on a blockchain concept to orchestrate the software development process where production is controlled by a similar infrastructure based on the working principles of blockchain. We discuss the model that integrates blockchain with the software development process, and provide some recommendations for future work to address the issues while orchestrating software production.
Citation - Scopus: 0
Augmented reality based continuous onboarding framework
(CEUR-WS, 2018) Ohri, İ.; Öge, İ.; Orkun, B.; Yılmaz, M.; Tüzün, E.
Having an efficient and effective onboarding process for a newcoing employee is a very important factor for the following work performance. For this reason, the orientation process is a process that should be well assessed both in terms of company and employees. Based on the fact that using virtual objects in the real environment enhances the efficiency in learning new things, in this project, the onboarding process is managed by augmented reality (AR) technology. One of the main objectives of the project is guiding the software engineers effectively with the help of augmented reality by providing them interactive communication between their colleagues and the projects.

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