Computer Engineering / Bilgisayar Mühendisliği

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  • Article
    Citation - Scopus: 3
    Development of Chrono-Spectral Gold Nanoparticle Growth Based Plasmonic Biosensor Platform
    (Elsevier, 2024) Sözmen, Alper Baran; Elveren, Beste; Erdoğan, Duygu; Mezgil, Bahadır; Baştanlar, Yalın; Yıldız, Ümit Hakan; Arslan Yıldız, Ahu
    Plasmonic sensor platforms are designed for rapid, label-free, and real-time detection and they excel as the next generation biosensors. However, current methods such as Surface Plasmon Resonance require expertise and well-equipped laboratory facilities. Simpler methods such as Localized Surface Plasmon Resonance (LSPR) overcome those limitations, though they lack sensitivity. Hence, sensitivity enhancement plays a crucial role in the future of plasmonic sensor platforms. Herein, a refractive index (RI) sensitivity enhancement methodology is reported utilizing growth of gold nanoparticles (GNPs) on solid support and it is backed up with artificial neural network (ANN) analysis. Sensor platform fabrication was initiated with GNP immobilization onto solid support; immobilized GNPs were then used as seeds for chrono-spectral growth, which was carried out using NH2OH at varied incubation times. The response to RI change of the platform was investigated with varied concentrations of sucrose and ethanol. The detection of bacteria E.coli BL21 was carried out for validation as a model microorganism and results showed that detection was possible at 102 CFU/ml. The data acquired by spectrophotometric measurements were analyzed by ANN and bacteria classification with percentage error rates near 0% was achieved. The proposed LSPR-based, label-free sensor application proved that the developed methodology promises utile sensitivity enhancement potential for similar sensor platforms. © 2024 The Author(s)
  • Article
    Citation - WoS: 1
    Citation - Scopus: 3
    Automatic Test Sequence Generation and Functional Coverage Measurement From Uml Sequence Diagrams
    (Igi Global, 2023) Ekici, Nazim Umut; Tuglular, Tugkan
    Sequence diagrams define functional requirements through use cases. However, their visual form limits their usability in the later stages of the development life cycle. This work proposes a method to transform sequence diagrams into graph-based event sequence graphs, allowing the application of graph analysis methods and defining graph-based coverage criteria. This work explores these newfound abilities in two directions. The first is to use coverage criteria along with existing tests to measure their coverage levels, providing a metric of how well they address the scenarios defined in sequence diagrams. The second is to use coverage criteria to automatically generate effective and efficient acceptance test cases based on the scenarios defined in sequence diagrams. The transformation method is validated with over eighty non-trivial projects. The complete method is validated through a non-trivial example. The results show that the test cases generated with the proposed method are more effective at exposing faults and more efficient in test input size than user-generated test cases.
  • Article
    Endüstriyel Nesnelerin İnterneti Uygulamaları için Fpga Destekli ve Bağlam Tabanlı Erişim Kontrol Güvenlik Sistemi
    (2023) Ercan, Ahmet Tuncay; Genç, Didem; Tomur, Emrah
    Endüstri 4.0 ile birlikte üretimin her alanında gittikçe artan bilgisayar destekli sistemlerin yarattığı farklı ve karmaşık ağ topolojileri, artan veri miktarı, firmaların güvenlik ihtiyaçlarını artırmaktadır. Bundan dolayı farklı endüstriyel sektörlerde kullanılan farklı cihaz ve veri kullanımı şirketler, kendi kritik akıllı üretim sistemlerine yönelik güvenilir bir risk yönetim sistemine ihtiyaç duymaktadır. İşletmeler bu yüzden sahip oldukları Endüstriyel Kontrol ve Bilişim Sistemlerini korumayı amaçlarlar. Bu çalışmada üretim alanında kullanılabilecek, endüstriyel cihazlar ve/veya bunlara bağlı sensörlerin erişim kontrolü bağlamında güvenlik ihtiyaçlarını karşılayacak ve kenar bilişim kapsamında çalışacak FPGA (Alanda Programlanabilir Kapı Dizileri) destekli bir güvenlik platformu tasarlanmış ve çalışma yöntemi açıklanmıştır. Akıllı üretim cihazlarının bulunduğu bir imalathane ortamında çalışan cihaz, sensor, akıllı kontrol kutusu ve ağ geçidi gibi bileşenler üzerinde bağlam-tabanlı bir erişim denetim sistemi kullanımı gösterilmiş ve örnek bir çoklu kimlik doğrulama yöntemi tasarlanmıştır.
  • Article
    Citation - Scopus: 5
    Unifying Behavioral and Feature Modeling for Testing of Software Product Lines
    (World Scientific Publishing, 2023) Belli, Fevzi; Tuğlular, Tuğkan; Ufuktepe, Ekincan
    Existing software product line (SPL) engineering testing approaches generally provide positive testing that validates the SPL's functionality. Negative testing is commonly neglected. This research aims to unify behavioral and feature models of an SPL, enable testing before and after variability binding for domain-centric and product-centric testing, and combine positive and negative testing for a holistic testing view. This study suggests behavioral modeling with event sequence graphs (ESGs). This heterogeneous modeling strategy supports bottom-up domain testing and top-down product testing with the feature model. This new feature-oriented ESG test creation method generates shorter test sequences than the original ESG optimum test sequences. Statechart and original ESG test-generating methods are compared. Positive testing findings are similar. The Statechart technique generated 12 test cases with 59 events, whereas the ESG technique created six test cases with 60 events. The ESG technique generated 205 negative test cases with 858 events with the Test Suite Designer tool. However, the Conformiq Designer tool for the Statechart technique does not have a negative test case generation capability. It is shown that the proposed ESG-based holistic approach confirms not only the desirable (positive) properties but also the undesirable (negative) ones. As an additional research, the traditional ESG test-generating approach is compared to the new feature-oriented method on six SPLs of different sizes and features. Our case study results show that the traditional ESG test generation approach demonstrated higher positive test generation scores compare to the proposed feature-oriented test generation approach. However, our proposed feature-oriented test generation approach is capable of generating shorter test sequences, which could be beneficial for reducing the execution time of test cases compared to traditional ESG approach. Finally, our case study has also shown that regardless of the test generation approach, there has been found no significant difference between the Bottom-up and Top-down test strategies with respect to their positive test generation scores. © World Scientific Publishing Company.
  • Article
    Link Prediction for Completing Graphical Software Models Using Neural Networks
    (IEEE, 2023) Leblebici, Onur; Tuğlular, Tuğkan; Belli, Fevzi
    Deficiencies and inconsistencies introduced during the modeling of software systems may result in high costs and negatively impact the quality of all developments performed using these models. Therefore, developing more accurate models will aid software architects in developing software systems that match and exceed expectations. This paper proposes a graph neural network (GNN) method for predicting missing connections, or links, in graphical models, which are widely employed in modeling software systems. The proposed method utilizes graphs as allegedly incomplete, primitive graphical models of the system under consideration (SUC) as input and proposes links between its elements through the following steps: (i) transform the models into graph-structured data and extract features from the nodes, (ii) train the GNN model, and (iii) evaluate the performance of the trained model. Two GNN models based on SEAL and DeepLinker are evaluated using three performance metrics, namely cross-entropy loss, area under curve, and accuracy. Event sequence graphs (ESGs) are used as an example of applying the approach to an event-based behavioral modeling technique. Examining the results of experiments conducted on various datasets and variations of GNN reveals that missing connections between events in an ESG can be predicted even with relatively small datasets generated from ESG models. Author
  • Article
    Citation - WoS: 9
    Citation - Scopus: 13
    Microservice-Based Projects in Agile World: a Structured Interview
    (Elsevier, 2024) Unlu, Huseyin; Kennouche, Dhia Eddine; Soylu, Gorkem Kiling; Demirors, Onur
    Context: During the last decade, Microservice-based software architecture (MSSA) has been a preferred design paradigm for a growing number of companies. MSSA, specifically in the form of reactive systems, has substantial differences from the more conventional design paradigms, such as object-oriented analysis and design. Therefore, adaptation demands software organizations to transform their culture. However, there is a lack of research studies that explore common practices utilized by software companies that implement MSSAs.Objective: In this study, our goal is to get an insight into how practices such as an agile methodology, software analysis, design, test, size measurement, and effort estimation are performed in software projects which embrace the Microservice-based software architecture paradigm. Together with the identification of practices utilized for the MSSA paradigm, we aim to determine the challenges organizations face to adopt microservice-based software architectures.Method: We performed a structured interview with participants coming from 20 different organizations over different roles, domains, and countries to collect information on their views, experience, and the challenges faced.Results: Our results reveal that organizations find agile development compatible with microservices. In general, they continue to use traditional object-oriented modeling notations for analysis and design in an abstract way. They continue to use the same subjective size measurement and effort estimation approaches that they were using previously in traditional architectures. However, they face unique challenges in developing microservices.Conclusion: Although organizations face challenges, practitioners continue to use familiar techniques that they have been using for traditional architectures. The results provide a snapshot of the software industry that utilizes microservices.
  • Article
    Citation - WoS: 1
    Citation - Scopus: 1
    How Software Practitioners Perceive Work-Related Barriers and Benefits Based on Their Educational Backgrounds: Insights From a Survey Study
    (IEEE, 2023) Ünlü, Hüseyin; Yürüm, Ozan Raşit; Özcan Top, Özden; Demirörs, Onur
    Survey results show that software practitioners from nonsoftware-related backgrounds face more barriers, have fewer benefits, and feel less satisfied in their work life. However, these differences reduce with more than 10 years of experience and involvement in software-related graduate programs, certificates, and mentorship.
  • Article
    Spectral Test Generation for Boolean Expressions
    (World Scientific Publishing, 2023) Ayav, Tolga
    This paper presents a novel method for testing Boolean expressions. It is based on spectral, aka Fourier analysis of Boolean functions which is exploited to generate test inputs. The approach has three important contributions: (i) It generates a relatively small test suite with a high capability of fault detection, (ii) The test suite is prioritized such that expected fault detection time is shorter, (iii) It is entirely mathematical relying on a simple and straightforward formula. The proposed method is formulated and evaluations are performed on both synthetic and real expressions. It is also compared with two common test generation criteria, MC/DC and Minimal MUMCUT. Evaluations show that the test suite generated by the spectral approach is relatively small while expressing the capability of a better and quicker fault detection. The approach presented in this paper provides a useful insight into how spectral/Fourier analysis of Boolean functions can be exploited in software testing.
  • Article
    Yazılım Ürün Hatlarında Tam Üründen Özellik Eksiltme Yoluyla Frklı Ürün Yapılandırmalarını Otomatik Üretme Yöntemi
    (2023) Öztürk Kaya, Dilek; Tuğlular, Tuğkan
    Yazılım ürün hattı (YÜH) karmaşık, büyük ölçekli ve ürün yapılandırması bakımından zengin yazılım sistemleri geliştirmek için gelelecek vadeden bir yaklaşımdır. Yazılım ürün hattındaki sayısı çok fazla olabilen ürün yapılandırmalarına ait modellerin otomatik elde edilmesi zaman ve maliyet kısıtları açısından oldukça önemlidir. Bu çalışmada, ürün modellerini daha üretken ve etkili şekilde elde edebilmek için, tam ürün modelinden, özellik eksiltme yoluyla farklı ürün yapılandırmalarına ait modelleri otomatik olarak elde etmeyi sağlayan bir yaklaşım önerdik. Önerilen yaklaşımı İçecek Otomatı YÜH, Banka Hesabı YÜH ve Öğrenci Yoklama Sistemi YÜH isimli üç farklı vaka çalışması üzerinde denedik. Özellik-bağımlılık ağacı ve dinamik kenar eşleme algoritması bu çalışmada önerilen özgün kavramlardır.
  • Article
    Citation - WoS: 2
    Citation - Scopus: 3
    Mutation-Based Minimal Test Suite Generation for Boolean Expressions
    (World Scientific Publishing, 2023) Ayav, Tolga; Belli, Fevzi
    Boolean expressions are highly involved in control flows of programs and software specifications. Coverage criteria for Boolean expressions aim at producing minimal test suites to detect software faults. There exist various testing criteria, efficiency of which is usually evaluated through mutation analysis. This paper proposes an integer programming-based minimal test suite generation technique relying on mutation analysis. The proposed technique also takes into account the cost of fault detection. The technique is optimal such that the resulting test suite guarantees to detect all the mutants under given fault assumptions, while maximizing the average percentage of fault detection of a test suite. Therefore, the approach presented can also be considered as a reference method to check the efficiency of any common technique. The method is evaluated using four well-known real benchmark sets of Boolean expressions and is also exemplary compared with MCDC criterion. The results show that the test suites generated by the proposed method provide better fault coverage values and faster fault detection.