Computer Engineering / Bilgisayar Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/10

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Now showing 1 - 10 of 38
  • Conference Object
    Citation - Scopus: 12
    Incremental Itemset Mining Based on Matrix Apriori Algorithm
    (Springer Verlag, 2012) Oğuz, Damla; Ergenç, Belgin
    Databases are updated continuously with increments and re-running the frequent itemset mining algorithms with every update is inefficient. Studies addressing incremental update problem generally propose incremental itemset mining methods based on Apriori and FP-Growth algorithms. Besides inheriting the disadvantages of base algorithms, incremental itemset mining has challenges such as handling i) increments without re-running the algorithm, ii) support changes, iii) new items and iv) addition/deletions in increments. In this paper, we focus on the solution of incremental update problem by proposing the Incremental Matrix Apriori Algorithm. It scans only new transactions, allows the change of minimum support and handles new items in the increments. The base algorithm Matrix Apriori works without candidate generation, scans database only twice and brings additional advantages. Performance studies show that Incremental Matrix Apriori provides speed-up between 41% and 92% while increment size is varied between 5% and 100%.
  • Conference Object
    Citation - Scopus: 6
    A Comprehensive Evaluation of Agile Maturity Self-Assessment Surveys
    (Springer Verlag, 2018) Yürüm, Ozan Raşit; Demirörs, Onur; Rabhi, Fethi
    Agile methodologies are adapted by growing number of software organizations. Agile maturity (also called agility) assessment is a way to ascertain the degree of this adoption and determine a course of action to improve agile maturity. There are a number of agile maturity assessment surveys in order to assess team or organization agility and many of them require no guidance. However, the usability of these surveys are not widely studied. The purpose of this study is to determine available agile maturity self-assessment surveys and evaluate their strengths and weaknesses for agile maturity assessment. An extensive case study is conducted to measure the sufficiency of 22 available agile maturity self-assessment surveys according to the seven expected features: comprehensiveness, fitness for purpose, discriminativeness, objectivity, conciseness, generalizability, and suitability for multiple assessment. Our case study results show that they do not satisfy all of the expected features fully but are helpful in some degree based on the purpose of usage.
  • Conference Object
    Citation - Scopus: 2
    Adapting Spice for Development of a Reference Model for Building Information Modeling - Bim-Carem
    (Springer Verlag, 2018) Yılmaz, Gökçen; Akçamete, Aslı; Demirörs, Onur
    Building Information Modelling (BIM) is highly adopted by Architecture, Engineering, Construction and Facilities Management (AEC/FM) companies around the world due to its benefits such as improving collaboration of stakeholders in projects. Effective implementation of BIM in organizations requires assessment of existing BIM performances of AEC/FM processes. We developed a reference model for BIM capability assessments based on the meta-model of the ISO/IEC 330xx (the most recent version of SPICE) family of standards. BIM-CAREM can be used for identifying the BIM capabilities of the AEC/FM processes. The model was updated iteratively based on the expert reviews and an exploratory case study, and was evaluated via four explanatory case studies. The assessment results showed that the BIM-CAREM is capable of identifying BIM capabilities of specific processes. In this paper, we present how we utilized ISO/IEC 330xx for developing BIM-CAREM as well as the iterations of the model and one of the explanatory case studies as an example.
  • Conference Object
    Citation - Scopus: 14
    Systematic Mapping Study on Process Mining in Agile Software Development
    (Springer Verlag, 2018) Erdem, Sezen; Demirörs, Onur; Rabhi, Fethi
    Process mining is a process management technique that allows for the analysis of business processes based on the event logs and its aim is to discover, monitor and improve executed processes by extracting knowledge from event logs readily available in information systems. The popularity of agile software development methods has been increasing in the software development field over the last two decades and many software organizations develop software using agile methods. Process mining can provide complementary tools to Agile organizations for process management. Process mining can be used to discover agile processes followed by agile teams to establish the baselines and to determine the fidelity or they can be used to obtain feedback to improve agility. Despite the potential benefit of using process mining for agile software development, there is a lack of research that systematically analyzes the usage of process mining in agile software development. This paper presents a systematic mapping study on usage of process mining in agile software development approaches. The aim is to find out the usage areas of process mining in agile software development, explore commonly used algorithms, data sources, data collection mechanisms, analysis techniques and tools. The study has shown us that process mining is used in Agile software development especially for the purpose of process discovery from task tracking applications. We also observed that source code repositories are main data sources for process mining, a diversity of algorithms are used for analysis of collected data and ProM is the most widely used analysis tool for process mining.
  • Conference Object
    Citation - Scopus: 1
    Measuring Change in Software Projects Through an Earned Value Lens
    (Springer Verlag, 2018) Efe, Pınar; Demirörs, Onur; Benetallah, Boualem
    Earned Value Management (EVM) is a common performance management tool for project management. EVM enables depicting the project progress in terms of scope, cost and schedule and provides future predictions based on trends and patterns. Even though EVM is widely used in various disciplines like manufacturing and construction, it is not common in software industry. One reason for this underutilization is the mismatch of an inherent nature of the software projects and the traditional EVM. Traditional EVM ignores change effort but it is predominant in software projects. We have developed cEVM as an extension to the traditional EVM to incorporate change and subsequent rework and evolution costs to measure earned value in software development projects more accurately. In this study, we focus on two applications of cEVM we performed to explore the usability of cEVM and to compare cEVM with traditional EVM. This paper discusses the results of the case studies as well as benefits and difficulties of cEVM.
  • Conference Object
    Citation - Scopus: 3
    Ontology Supported Policy Modeling in Opinion Mining Process
    (Springer Verlag, 2012) Husaini, Mus'ab; Ko, Andrea; Tapucu, Dilek; Saygın, Yücel
    In e-Society the spreading services offered by Social Web has changed the way of communication and cooperation among citizens, policy-makers, governance bodies and civil society actors. One of the main goals of policymakers is to motivate citizens for participation in policy-making processes. UbiPOL ((Ubiquitous Participation Platform for Policy-making, ICT-2009.7.3(ICT for Governance and Policy Modelling), 2009-2011) aimed to develop a ubiquitous solution, which emphasizes citizens' participation in policy-making processes (PMPs) regardless of their current location and time. Ontology-based opinion mining component of Ubipol system has a crucial role in citizens' commitment, because it empowers them to contribute in policy making. This paper presents the ontology-based semi-automatic approach and tool for sentiment analysis in Ubipol system, which include lexicon extraction from a large corpus of documents. Aspect-based opinion summarization of user reviews and its combination with domain ontology development are discussed as well.
  • Conference Object
    Citation - WoS: 11
    Citation - Scopus: 20
    Learning Styles Diagnosis Based on Learner Behaviors in Web Based Learning
    (Springer Verlag, 2009) Atman, Nilüfer; İnceoğlu, Mustafa Murat; Aslan, Burak Galip
    Individuals have different backgrounds, motivation and preferences in their own learning processes. Web-based systems that ignore these differences have difficulty in meeting learners' needs effectively. One of these individual differences is the learning style. For providing adaptively incorporated learning styles, firstly learning styles of learners have to be identified. There are many different learning models in literature. This study is based on Felder and Silverman's Learning Styles Model and investigates only active/reflective and visual/verbal dimensions of this model. Instead of filling out a questionnaire, learner behaviors are analyzed with the help of literature-based approaches so that learning styles of learners can be detected.
  • Conference Object
    Citation - Scopus: 2
    Adaptive Join Operator for Federated Queries Over Linked Data Endpoints
    (Springer Verlag, 2016) Oğuz, Damla; Yin, Shaoyi; Hameurlain, Abdelkader; Ergenç, Belgin; Dikenelli, Oğuz
    Traditional static query optimization is not adequate for query federation over linked data endpoints due to unpredictable data arrival rates and missing statistics. In this paper, we propose an adaptive join operator for federated query processing which can change the join method during the execution. Our approach always begins with symmetric hash join in order to produce the first result tuple as soon as possible and changes the join method as bind join when it estimates that bind join is more efficient than symmetric hash join for the rest of the process. We compare our approach with symmetric hash join and bind join. Performance evaluation shows that our approach provides optimal response time and has the adaptation ability to the different data arrival rates.
  • Article
    Citation - WoS: 4
    Citation - Scopus: 5
    Generating Ontologies From Relational Data With Fuzzy-Syllogistic Reasoning
    (Springer Verlag, 2015) Kumova, Bora İsmail
    Existing standards for crisp description logics facilitate information exchange between systems that reason with crisp ontologies. Applications with probabilistic or possibilistic extensions of ontologies and reasoners promise to capture more information, because they can deal with more uncertainties or vagueness of information. However, since there are no standards for either extension, information exchange between such applications is not generic. Fuzzy-syllogistic reasoning with the fuzzy-syllogistic system4S provides 2048 possible fuzzy inference schema for every possible triple concept relationship of an ontology. Since the inference schema are the result of all possible set-theoretic relationships between three sets with three out of 8 possible fuzzy-quantifiers, the whole set of 2048 possible fuzzy inferences can be used as one generic fuzzy reasoner for quantified ontologies. In that sense, a fuzzy syllogistic reasoner can be employed as a generic reasoner that combines possibilistic inferencing with probabilistic ontologies, thus facilitating knowledge exchange between ontology applications of different domains as well as information fusion over them.
  • Conference Object
    Citation - Scopus: 4
    An Aspect-Lexicon Creation and Evaluation Tool for Sentiment Analysis Researchers
    (Springer Verlag, 2012) Husaini, Mus'ab; Koçyiğit, Ahmet; Tapucu, Dilek; Yanıkoğlu, Berrin; Saygın, Yücel
    In this demo paper, we present SARE, a modular and extendable semi-automatic system that 1) assists researchers in building gold-standard lexicons and evaluating their lexicon extraction algorithms; and 2) provides a general and extendable sentiment analysis environment to help researchers analyze the behavior and errors of a core sentiment analysis engine using a particular lexicon.