Mühendislik ve Doğa Bilimleri Fakültesi

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    A framework for applying the principles of depth perception to information visualization
    (ACM, 2010) Çipiloğlu Yıldız, Zeynep; Bülbül, Abdullah; Capin, Tolga; Çipiloğlu Yıldız, Zeynep; Fakülteler > Mühendislik Ve Doğa Bilimleri Fakültesi > Bilgisayar Mühendisliği Bölümü
    During the visualization of 3D content, using the depth cues selectively to support the design goals and enabling a user to perceive the spatial relationships between the objects are important concerns. In this novel solution, we automate this process by proposing a framework that determines important depth cues for the input scene and the rendering methods to provide these cues. While determining the importance of the cues, we consider the user’s tasks and the scene’s spatial layout. The importance of each depth cue is calculated using a fuzzy logic–based decision system. Then, suitable rendering methods that provide the important cues are selected by performing a cost-profit analysis on the rendering costs of the methods and their contribution to depth perception. Possible cue conflicts are considered and handled in the system. We also provide formal experimental studies designed for several visualization tasks. A statistical analysis of the experiments verifies the success of our framework.
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    The extension-based inference algorithm for pD
    (Elsevier, 2012-02) Öztürk, Övünç; Özacar Öztürk, Tuğba; Ünalır, Murat Osman; Öztürk, Övünç; Özacar Öztürk, Tuğba; Fakülteler > Mühendislik Ve Doğa Bilimleri Fakültesi > Bilgisayar Mühendisliği Bölümü
    In this work, we present a scalable rule-based reasoning algorithm for the OWL pD* language. This algorithm uses partial materialization and a syntactic ontology transformation (the extension-based knowledge model) to provide a fast inference. Because the materialized part of the ontology does not contain assertional data, the time consumed by the process, and the number of inferred triples, remain fixed with varying amounts of assertional data. The algorithm uses database reasoning and a query rewriting technique to handle the remaining inference. The extension-based knowledge model and the database reasoning prevent the expected decreases in query performances, which are the natural result of online reasoning during query time. This work also evaluates the efficiency of the proposed method by conducting experiments using LUBM and UOBM benchmarks.
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    Improvement of intramolecular charge transfer within a donor–acceptor blend by doping novel synthesized benzothiadiazole small molecules in solid state
    (Optical Materials, 2014) Dinçalp, Haluk; Murat, Gözde; İçli, Sıddık; Dinçalp, Haluk; Murat, Gözde; Fakülteler > Mühendislik Ve Doğa Bilimleri Fakültesi > Kimya Bölümü
    Three electron-deficient small molecules based on 2,1,3-benzothiadiazole (BTD) units namely, 4,7-bis (3-methoxyphenyl)-2,1,3-benzothiadiazole (BT1), (3-{7-[3-(dimethylamino)phenyl]-2,1,3-benzothiadi azole-4-yl}phenyl)dimethylamine (BT2) and 3,30 -(2,1,3-benzothiadiazole-4,7-dyl)dianiline (BT3) were synthesized and their photophysical properties were investigated systematically to understand their potential usage in ternary organic solar cells (OSCs) as additive material to enhance the cell efficiency. All these molecules show broad absorption bands in 350–750 nm on glass substrate and their optical band gaps were calculated to be around 2.50–2.80 eV. BTD fluorescence dynamics were measured in polymer:BT1:fullerene blends with varying emission wavelengths of active layer. Fluorescence emission and time resolved measurements indicated photoinduced energy shift from BT1 dye to fullerene and also from polymer to BT1 dye upon excitation of the active layer.
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    A perceptual quality metric for dynamic triangle meshes
    (Springer International Publishing, 2017) Çipiloğlu Yıldız, Zeynep; Capin, Tolga; Çipiloğlu Yıldız, Zeynep; Fakülteler > Mühendislik Ve Doğa Bilimleri Fakültesi > Bilgisayar Mühendisliği Bölümü
    A measure for assessing the quality of a 3D mesh is necessary in order to determine whether an operation on the mesh, such as watermarking or compression, affects the perceived quality. The studies on this field are limited when compared to the studies for 2D. In this work, we aim a full-reference perceptual quality metric for animated meshes to predict the visibility of local distortions on the mesh surface. The proposed visual quality metric is independent of connectivity and material attributes. Thus, it is not associated to a specific application and can be used for evaluating the effect of an arbitrary mesh processing method. We use a bottom-up approach incorporating both the spatial and temporal sensitivity of the human visual system. In this approach, the mesh sequences go through a pipeline which models the contrast sensitivity and channel decomposition mechanisms of the HVS. As the output of the method, a 3D probability map representing the visibility of distortions is generated. We have validated our method by a formal user experiment and obtained a promising correlation between the user responses and the proposed metric. Finally, we provide a dataset consisting of subjective user evaluation of the quality of public animation datasets.
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    A semantic web case study: representing the ephesus museum collection using erlangen CRM ontology
    (Springer Verlag, 2017-11) Özacar Öztürk, Tuğba; Öztürk, Övünç; Yüksel, Fulya; Lobaba, Salloutah; Abdülbaki, Baraa; Bilici, Elif; Özacar Öztürk, Tuğba; Öztürk, Övünç; Fakülteler > Mühendislik Ve Doğa Bilimleri Fakültesi > Bilgisayar Mühendisliği Bölümü
    Cultural heritage has recently become an important application area for Semantic Web technologies. Semantic Web technologies and ontologies provide a solution for intelligent integration of heterogeneous data about the cultural heritage. The objective of this paper is the construction of an ontology for the cultural heritage related to Selçuk region in Western Turkey. We use a subset of the Erlangen CRM as our ontology schema, then we populate the ontology with 814 objects in the Ephesus Museum. One of the objectives of this work is to integrate the ontology with other projects which use Erlangen CRM as ontology schema. Therefore, we present an integration case study that aggregates content from Ephesus Museum and British Museum.
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    Klasik Türk müziğinde makam tanıma için veri madenciliği kullanımı
    (Gazi Üniversitesi, 2017-12) Abidin, Didem; Özacar, Tuğba; Öztürk, Övünç; Abidin, Didem; Özacar, Tuğba; Öztürk, Övünç; Fakülteler > Mühendislik Ve Doğa Bilimleri Fakültesi > Bilgisayar Mühendisliği Bölümü
    Müzik eserlerinin sayısal ortama aktarılmasıyla birlikte, bilgisayar bilimleri müzikoloji çalışmalarının içerisinde kendine yer bulmaya başlamıştır. Müzik eserleri bilimsel araştırmalarda veri olarak kullanılmakta ve hesaplamalı müzik alanı bu alanda yapılan çalışmalar ile hızla gelişmektedir. Her ne kadar yapılan çalışmaların büyük bir bölümü sembolik olarak ifade edilmesi daha kolay olan Batı Müziği eserleri üzerine olsa da, Türk Müziği eserleri de artık çeşitli çalışmaların konusu olmaktadır. Türk Müziğinin temeli olan makam sistemi, bilgisayar bilimleri ile uğraşan araştırmacıların dikkatini çekmiş ve Türk Müziği eserler veri madenciliği, makine öğrenmesi, sınıflandırma gibi çalışmaların konusu olmuştur. Bu çalışmada, bir ses dosyasından nota tanıma ile elde edildiği varsayılan ve 1261 Türk Müziği eserine ait sadece nota dizilerini içeren veri dosyası üzerinde makine öğrenmesi metodu ile makam tahmini yapmaya yönelik deneysel bir çalışma gerçekleştirilmiştir. Music XML biçimindeki eserlerin makine öğrenmesi uygulamasında kullanılabilmesi amacıyla bir yazılım geliştirilmiş, bu yazılımla makine öğrenmesinde başarımı arttırmak için özgün veri kümesine dört farklı türetilmiş veri sahası eklenmiştir. Sonuç olarak, ‘Rastgele Orman’algoritması ile makam tanımada %89,7 oranında başarım gözlemlenmiştir.
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    Optoelectronic performance comparison of new thiophene linked benzimidazole conjugates with diverse substitution patterns
    (Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2018) Dinçalp, Haluk; Murat Saltan, Gözde; Kırmacı, Eser; Kıran, Merve; Zafer, Ceylan; Dinçalp, Haluk; Murat Saltan, Gözde; Fakülteler > Mühendislik Ve Doğa Bilimleri Fakültesi > Kimya Bölümü
    In an approach to develop efficient organic optoelectronic devices to be used in light-driven systems, a series of three thiophene linked benzimidazole conjugates were synthesized and characterized. The combination of two thiophene rings to a benzimidazole core decorated with different functional groups (such as \\OCH3, \\N(CH3)2,\\CF3) resulted in donor-acceptor type molecular scaffold. The effect of the electronic behavior of the substituents on the optical, electrochemical, morphological and electron/hole transporting properties of the dyes were systematically investigated. DTBI2 dye exhibited distinct absorption properties among the other studied dyes because N,N-dimethylamino group initiated intramolecular charge transfer (ICT) process in the studied solvents. In solid state, the dyes exhibit peaks extending up to 600 nm. Depending on the solvent polar ities, dyes show significant wavelength changes on their fluorescence emission spectra in the excited states. Mor phological parameters of the thin films spin-coated from CHCl3 solution were investigated by using AFM instrument; furthermore photovoltaic responses are reported, even though photovoltaic performances of thefabricated solar cells with different configurations are quite low.
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    A machine learning framework for full-reference 3D shape quality assessment
    (Springer Berlin Heidelberg, 2018) Çipiloğlu Yıldız, Zeynep; Öztireli, A. Cengiz; Capin, Tolga; Çipiloğlu Yıldız, Zeynep; Fakülteler > Mühendislik Ve Doğa Bilimleri Fakültesi > Bilgisayar Mühendisliği Bölümü
    To decide whether the perceived quality of a mesh is influenced by a certain modification such as compressionors implification, a metric for estimating the visual quality of 3D meshes is required. Today, machine learning and deep learning techniques are getting increasingly popular since they present efficient solutions to many complex problems. However, these techniques are not much utilized in the field of 3D shape perception. We propose a novel machine learning-based approach for evaluating the visual quality of 3D static meshes. The novelty of our study lies in incorporating crowdsourcing in a machine learning framework for visual quality evaluation. We deliberate that this is an elegant way since modeling human visual system processes is a tedious task and requires tuning many parameters. We employ crowdsourcing methodology for collecting data of quality evaluations and metric learning for drawing the best parameters that well correlate with the human perception. Experimental validation of the proposed metric reveals a promising correlation between the metric output and human perception. Results of our crowdsourcing experiments are publicly available for the community.
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    Buz pateni öğrenenler için hareket algılama tabanlı bir sistem tasarımı
    (Institute of Electrical and Electronics Engineers Inc., 2018-05) Öztürk, Övünç; Kahramanlı, Murat Mecit; Öztürk, Övünç; Fakülteler > Mühendislik Ve Doğa Bilimleri Fakültesi > Bilgisayar Mühendisliği Bölümü
    Bu bildiride buz patenini yeni öğrenmeye başlayanlar için hareket algılama tabanlı, ergonomik, kurulumu basit ve taşınabilir bir sistem tasarımı sunulmaktadır. Sistem kullanıcıların temel kayma tekniklerini doğru bir şekilde uygulamasına destek olacaktır. Sistem tasarlanırken, geliştirmeye açık, esnek ve modüler olmasına dikkat edilmiştir. Böylece, daha ileri seviye tekniklerin kontrolünün sağlanması veya sistemin vücut koordinasyonu gerektiren diğer sporlar için adaptasyonu daha kolay bir şekilde gerçekleştirilebilecektir. Sistemin temel destek elemanları ataletsel ölçüm birimleridir. Sistemdeki ataletsel ölçüm birimi bile¸senleri bedenin her bir uzvunun yön vektörünü belirlemektedir. Bu sensörlerden gelen veriler aracılığıyla belirlenmiş olan yönler, sistemde kullanıcıyı doğru bir şekilde yönlendirmek için altyapı oluşturmaktadır. Kullanıcı kulaklıkları ve sensör modüllerini taktıktan sonra sensörlerden gelen veriler kullanılarak kullanıcıya sesli olarak açıkça anlaşılır, motive edici ve kısa komutlar verilecektir.
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    KORAL: Türk müziği için makam tabanlı öneri motoru tasarımı
    (Institute of Electrical and Electronics Engineers Inc., 2018-09) Öztürk, Övünç; Özacar Öztürk, Tuğba; Abidin, Didem; Öztürk, Övünç; Özacar Öztürk, Tuğba; Abidin, Didem; Fakülteler > Mühendislik Ve Doğa Bilimleri Fakültesi > Bilgisayar Mühendisliği Bölümü
    Bu çalışmada, tek bir Türk Sanat Müziği eserinden yola çıkarak makam ve usul yönünden benzer eserleri bulan ve fasıl niteliğinde bir çalma listesi oluşturabilen bir uygulama tasarımı anlatılmaktadır. Çalışmada kullanılan eserler bir çizgede tutulacak ve bu çizge bağlı veri olarak yayınlanacaktır. Bu bağlamda ilk defa Türk Sanat Müziği eserlerine yönelik bağlı veri standartlarında bir bilgi tabanı oluşturulmuş olacaktır.
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    A hybrid genetic - Differential evolution algorithm (HybGADE) for a constrained sequencing problem
    (Institute of Electrical and Electronics Engineers Inc., 2018-09-28) Abidin, Didem; Abidin, Didem; Fakülteler > Mühendislik Ve Doğa Bilimleri Fakültesi > Bilgisayar Mühendisliği Bölümü
    For researchers, evolutionary algorithms are mostly preferable because of their effectiveness in finding the optimum solutions to many problems. Among these problems, sequencing is one of the most popular. In daily life, it is a must to find the best solution to a sequencing problem in order to save time, money and labour. Education is also one of the application areas of optimization where sequencing matters. In this paper, a hybrid genetic - differential algorithm is introduced, which finds better solutions to sequencing problem in education. The correct order of educational data is crucial because it directly affects the students' performance. In this study, educational material of Database course in Ege University Tire Kutsan Vocational School Computer Programming Department is used as the data set with two different evolutionary algorithms (EA). In these data sets, there are some constraints which should be considered while sequencing. We called them “prerequisites” that tells us the rules about the order of the modules of a course. That is why, the study can be considered as an application of Precedence-Constrained Sequencing. The sequencing performances of pure genetic algorithm (GA) and hybridized differential evolution (DE) with genetic algorithms (HybGADE) are compared with a computer program implemented. It is observed that, HybGADE can be used with 99.54% of reliability where pure GA has an effectiveness of 98.53%. The percentage of the students passing the class has been observed for four years. The ratio of students passing the class has increased from 39% to 65%, which can be considered as a remarkable increase.
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    Simulation of glucose regulating mechanism with an agent-based software engineering tool
    (Balikesir University, 2019) Emek, Sevcan; Evren, Vedat; Bora, Şebnem; Emek, Sevcan; Fakülteler > Mühendislik Ve Doğa Bilimleri Fakültesi > Bilgisayar Mühendisliği Bölümü
    This study provides a detailed explanation of a regulating mechanism of the blood glucose levels by an agent-based software engineering tool. Repast Simphony which is used in implementation of this study is an agent-based software engineering tool based on the object-oriented programming using Java language. Agent-based modeling and simulation is a computational methodology for simulating and exploring phenomena that includes a large set of active components represented by agents. The agents are main components situated in space and time of agent-based simulation environment. In this study, we present hormonal regulation of blood glucose levels by our improved agent-based control mechanism. Hormonal regulation of blood glucose levels is an important process to maintain homeostasis inside the human body. We offer a negative feedback control mechanism with agent-based modeling approach to regulate the secretion of insulin hormone which is responsible for increasing the blood glucose levels. The negative feedback control mechanism run by three main agents that interact with each other to perform their local actions in the simulation environment. The result of this study shows the local behavior of the agents in the negative feedback loop and illustrates how to balance the blood glucose levels. Finally, this study which is thought a potential implementation of agent-based modeling and simulation may contribute to the exploration of other homeostatic control systems inside the human body.
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    A fully object-space approach for full-reference visual quality assessment of static and animated 3D meshes
    (SciTePress, 2019) Çipiloğlu Yıldız, Zeynep; Capin, Tolga; Çipiloğlu Yıldız, Zeynep; Fakülteler > Mühendislik Ve Doğa Bilimleri Fakültesi > Bilgisayar Mühendisliği Bölümü
    3D mesh models are exposed to several geometric operations such as simplification and compression. Several metrics for evaluating the perceived quality of 3D meshes have already been developed. However, most of these metrics do not handle animation and they measure the global quality. Therefore, a full-reference perceptual error metric is proposed to estimate the detectability of local artifacts on animated meshes. This is a bottom-up approach in which spatial and temporal sensitivity models of the human visual system are integrated. The proposed method directly operates in 3D mode space and generates a 3D probability map that estimates the visibility of distortions on each vertex throughout the animation sequence. We have also tested the success of our metric on public datasets and compared the results to other metrics. These results reveal a promising correlation between our metric and human perception.
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    OPPCAT: Ontology population from tabular data
    (SAGE Publications Ltd., 2019-02) Öztürk, Övünç; Öztürk, Övünç; Fakülteler > Mühendislik Ve Doğa Bilimleri Fakültesi > Bilgisayar Mühendisliği Bölümü
    In order to present large amount of information on the Web to both users and machines, it is urgently needed to structure Web data. E-commerce is one of the areas where increasing data bottlenecks on the Web inhibit data access. Ontological display of the product information enables better product comparison and search applications using the semantics of the product specifications and their corresponding values. In this article, we present a framework called OPPCAT, which is used for semi-automatic ontology population from tabular data in e-commerce stores and product catalogues. As a result, OPPCAT allows tabular data to be used for mass production of ontology content. First, we present the common patterns in tabular data which obstruct semi-automatic production of ontologies. Then, we suggest solutions which automatically fix these errors. Finally, we define an algorithm to build ontology content semi-automatically.
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    Onyx: A new Canvas-based tool for visualizing biomedical and health ontologies
    (Wiley, 2019-02) Öztürk, Övünç; Açıkgöz, Hasan Gökhan; Öztürk, Övünç; Fakülteler > Mühendislik Ve Doğa Bilimleri Fakültesi > Bilgisayar Mühendisliği Bölümü
    Ontologies provide formal, machine-readable, and human-interpretable representations of domain knowledge. Therefore, ontologies have come into question with the development of Semantic Web technologies. People who want to use ontologies need an understanding of the ontology, but this understanding is very difficult to attain if the ontology user lacks the background knowledge necessary to comprehend the ontology or if the ontology is very large. Thus, software tools that facilitate the understanding of ontologies are needed. Ontology visualization is an important research area because visualization can help in the development, exploration, verification, and comprehension of ontologies. This paper introduces the design of a new ontology visualization tool, which differs from traditional visualization tools by providing important metrics and analytics about ontology concepts and warning the ontology developer about potential ontology design errors. The tool, called Onyx, also has advantages in terms of speed and readability. Thus, Onyx offers a suitable environment for the representation of large ontologies, especially those used in biomedical and health information systems and those that contain many terms. It is clear that these additional functionalities will increase the value of traditional ontology visualization tools during ontology exploration and evaluation.
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    Effects of image filters on various image datasets
    (ICCTA, 2019-04-16) Abidin, Didem; Abidin, Didem; Fakülteler > Mühendislik Ve Doğa Bilimleri Fakültesi > Bilgisayar Mühendisliği Bölümü
    Image classification is a very common research area, on which researchers work with various classification techniques. The aim of this study is to apply different filters on four different datasets and evaluate their performances in image classification. The study was performed in WEKA environment with Random Forest algorithm and image filters are applied to the datasets one by one and as a combination. Filter combinations got better performance than applying single filter on data. Filter combinations got the worst result on artworks with a percentage of 83.42%. However they were very successful on classifying the images in natural images dataset with a performance of 99.76%.
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    Genetik algoritmalar kullanılarak metinlerde otomatik özet çıkarma
    (IEEE, 2020-01-07) Yaşa, Ahmet Cahit; Karcıoğlu, Abdullah Ammar; Yaşa, Ahmet Cahit; Fakülteler > Mühendislik Ve Doğa Bilimleri Fakültesi > Bilgisayar Mühendisliği Bölümü
    Automatic text summarization is one of the applications of natural language processing that has been studied for a long time. The increase in the amount of information in web resources has increased the need for automatic text summarization methods. It is difficult to design a system to produce abstracts created by human hands. For this reason, many researchers have focused on extracting sentences or paragraphs, which is a kind of summary. In this study, we introduce a method that was created using genetic algorithms to generate such summaries. After the texts are preprocessed, vocabulary is created and given as input to the proposed method. The sentence selection based on Genetic Algorithm is used to summarize and after that the summary is created, it is evaluated using the fitness function. In our first model, the fitness function is based on the frequency of each word and the word pair frequencies. The results of the applied model are discussed using the same dataset in another method based on tf-idf, with precision, recall, fscore and Rouge metrics.