Computer Engineering / Bilgisayar Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/10
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Article Citation - WoS: 41Citation - Scopus: 50Bim-Carem: Assessing the Bim Capabilities of Design, Construction and Facilities Management Processes in the Construction Industry(Elsevier, 2023) Gökçen, Yılmaz; Akçamete, Aslı; Demirörs, OnurBIM adoption has accelerated worldwide since it is an important enabling technology for digitalisation in the construction industry. Adopting BIM requires transforming the traditional building life cycle stages (planning, design, construction and facilities management) into BIM-integrated project deliveries. Assessing the BIM ca- pabilities of these stages helps organisations to identify gaps in their BIM uses and improve them. There is a lack of a comprehensive model in the literature for assessing the BIM capabilities of individual building life cycle stages and their processes. Existing assessment models focus on assessing the BIM maturity of construction projects and organisations which do not inform the required BIM improvements for individual stages and their processes. Hence, we iteratively developed the Building Information Modelling (BIM) Capability Assessment REference Model (BIM-CAREM) and demonstrated its usability through multiple explanatory case studies per- formed with two international design and engineering companies and two general contractors in Turkey. We assessed the BIM capabilities of design, construction and facility management processes of various buildings i.e. residential, stadiums, hospitals and airports. The results showed that the BIM capability levels of design, con- struction and facility management processes vary within and across the companies.Conference Object Citation - Scopus: 2Repository Landscape in Turkiye and Gcris: the First National Research Information System(Elsevier, 2022) Tuğlular, Tuğkan; Gürdal, Gültekin; Kafalı Can, Gönül; Özdemirden, Ahmet ŞemsettinThis paper describes the history and developments of research infrastructures and open science policies in Turkiye. Moreover, it focuses on the GCRIS (Grand Current Research Information Systems), Turkiye's first Research Information System by inter-national standards, emphasizing the need for internationally interoperable research infrastructures in Turkiye. GCRIS Research Information System, implemented on the open-source software DSpace-CRIS 6.3, was developed with data analytics in mind and continues to be improved by Research Ecosystems Inc. As a strategic partner, Izmir Institute of Technology (IZTECH) is the first university to use GCRIS. Other Universities have used GCRIS since then. With the increase in the number of universities using GCRIS, Turkiye's Research Ecosystem will be trackable and measurable much better thanks to GCRIS intelligent reporting sys- tem. Most importantly, not only the research outputs of Turkiye will be more visible, but also research infrastructures' integration will facilitate with the European Open Science Cloud (EOSC) and other initiatives worldwide.Article Citation - WoS: 1Citation - Scopus: 1Hybrid Probabilistic Timing Analysis With Extreme Value Theory and Copulas(Elsevier, 2022) Bekdemir, Levent; Bazlamaçcı, Cüneyt F.The primary challenge of time-critical systems is to guarantee that a task completes its execution before its deadline. In order to ensure compliance with timing requirements, it is necessary to analyze the timing behavior of the overall software. Worst-Case Execution Time (WCET) represents the maximum amount of time an individual software unit takes to execute and is used for scheduling analysis in safety-critical systems. Recent studies focus on statistical approaches, which augments measurement-based timing analysis with probabilistic confidence level by applying stochastic methods. Common approaches either utilize Extreme Value Theory (EVT) for end-to-end measurements or convolution techniques for a group of program units to derive probabilistic upper bounds for the program. The former method does not ensure path coverage while the latter suffers from ignoring possible extreme cases. Furthermore, current state-of-the-art convolution methods employed in a commercial WCET analysis tool overestimates the results because of using the assumption of worst-case dependence between basic blocks. In this paper, we propose a hybrid probabilistic timing analysis framework and modeling the program units with EVT to capture extreme cases and use Copulas to model the dependency between the units to derive tighter distributional bounds in order to mitigate the effects of co-monotonic assumptions.Article Citation - WoS: 7Citation - Scopus: 8Long-Term Image-Based Vehicle Localization Improved With Learnt Semantic Descriptors(Elsevier, 2022) Çınaroğlu, İbrahim; Baştanlar, YalınVision based solutions for the localization of vehicles have become popular recently. In this study, we employ an image retrieval based visual localization approach, in which database images are kept with GPS coordinates and the location of the retrieved database image serves as the position estimate of the query image in a city scale driving scenario. Regarding this approach, most existing studies only use descriptors extracted from RGB images and do not exploit semantic content. We show that localization can be improved via descriptors extracted from semantically segmented images, especially when the environment is subjected to severe illumination, seasonal or other long-term changes. We worked on two separate visual localization datasets, one of which (Malaga Streetview Challenge) has been generated by us and made publicly available. Following the extraction of semantic labels in images, we trained a CNN model for localization in a weakly-supervised fashion with triplet ranking loss. The optimized semantic descriptor can be used on its own for localization or preferably it can be used together with a state-of-the-art RGB image based descriptor in hybrid fashion to improve accuracy. Our experiments reveal that the proposed hybrid method is able to increase the localization performance of the standard (RGB image based) approach up to 7.7% regarding Top-1 Recall values.Article Citation - WoS: 12Citation - Scopus: 21A Change Management Model and Its Application in Software Development Projects(Elsevier, 2019) Efe, Pınar; Demirörs, OnurChange is inevitable in software projects and software engineers strive to find ways to manage changes. A complete task could be easily in a team's agenda sometime later due to change demands. Change demands are caused by failures and/or improvements and require additional effort which in most cases have not been planned upfront and affect project progress significantly. Earned Value Management (EVM) is a powerful performance management and feedback tool for project management. EVM depicts the project progress in terms of scope, cost, and schedule and provides future predictions based on trends and patterns of the past. Even though EVM works quite well and widely used in disciplines like construction and mining, it is not the case for software discipline. Software projects require special attention and adoption for change. In this study, we present a model to measure change and subsequent rework and evolution costs to monitor software projects accurately. We have performed five case studies in five different companies to explore the usability of the proposed model. This paper depicts the proposed model and discusses the results of the case studies.Article Citation - WoS: 2Citation - Scopus: 2Density-Aware Cellular Coverage Control: Interference-Based Density Estimation(Elsevier, 2019) Eroğlu, Alperen; Yaman, Okan; Onur, ErtanAs demand for mobile communications increases, cells have to become smaller to efficiently use the scarce spectrum and to increase capacity, and small-cell networks will hereby emerge. They may be large in scale and highly dynamic resembling ad hoc networks due to the moving base stations. The variations in the density of the small cell networks impact the quality of service and introduce many novel challenges such as coverage control. We propose two novel base station density estimators, the interference-based density estimator (IDE) and the multi-access edge cloud-based density estimator (CDE) in a three-dimensional field. The estimators employ received signal strength measurements. We validate these two density estimators by using Monte-Carlo simulations. Furthermore, we analyze the impact of density on network outage in cellular networks and propose a density-aware cell zooming technique. According to the observations, base station (BS) density affects network coverage significantly. Received signal strength (RSS)-based density estimators can easily be implemented and applied in the network communication stack although they are more prone to shadowing and fading. Under favour of the density-aware cell zooming method, the network outage can be managed dynamically by adapting the transmit power, which provides a self-configurable and -organized network. (C) 2019 Elsevier B.V. All rights reserved.Article Citation - WoS: 17Citation - Scopus: 19Pixelated Colorimetric Nucleic Acid Assay(Elsevier, 2020) Aydın, Hakan Berk; Cheema, Jamal Ahmed; Arnmanath, Gopal; Toklucu, Cihan; Yücel, Müge; Özenler, Sezer; Yıldız, Ümit HakanConjugated polyelectrolytes (CPEs) have been widely used as reporters in colorimetric assays targeting nucleic acids. CPEs provide naked eye detection possibility by their superior optical properties however, as concentration of target analytes decrease, trace amounts of nucleic acid typically yield colorimetric responses that are not readily perceivable by naked eye. Herein, we report a pixelated analysis approach for correlating colorimetric responses of CPE with nucleic acid concentrations down to 1 nM, in plasma samples, utilizing a smart phone with an algorithm that can perform analytical testing and data processing. The detection strategy employed relies on conformational transitions between single stranded nucleic acid-cationic CPE duplexes and double stranded nucleic acid-CPE triplexes that yield distinct colorimetric responses for enabling naked eye detection of nucleic acids. Cationic poly[N,N,N-triethyl-3-((4-methylthiophen-3-yl)oxy)propan-1-aminium bromide] is utilized as the CPE reporter deposited on a polyvinylidene fluoride (PVDF) membrane for nucleic acid assay. A smart phone application is developed to capture and digitize the colorimetric response of the individual pixels of the digital images of CPE on the PVDF membrane, followed by an analysis using the algorithm. The proposed pixelated approach enables precise quantification of nucleic acid assay concentrations, thereby eliminating the margin of error involved in conventional methodologies adopted for interpretation of colorimetric responses, for instance, RGB analysis. The obtained results illustrate that a ubiquitous smart phone could be utilized for point of care colorimetric nucleic acids assays in complex matrices without requiring sophisticated software or instrumentation.Article Citation - WoS: 16Citation - Scopus: 22Dgstream: High Quality and Efficiency Stream Clustering Algorithm(Elsevier, 2020) Ahmed, Rowanda; Dalkılıç, Gökhan; Erten, YusufRecently as applications produce overwhelming data streams, the need for strategies to analyze and cluster streaming data becomes an urgent and a crucial research area for knowledge discovery. The main objective and the key aim of data stream clustering is to gain insights into incoming data. Recognizing all probable patterns in this boundless data which arrives at varying speeds and structure and evolves over time, is very important in this analysis process. The existing data stream clustering strategies so far, all suffer from different limitations, like the inability to find the arbitrary shaped clusters and handling outliers in addition to requiring some parameter information for data processing. For fast, accurate, efficient and effective handling for all these challenges, we proposed DGStream, a new online-offline grid and density-based stream clustering algorithm. We conducted many experiments and evaluated the performance of DGStream over different simulated databases and for different parameter settings where a wide variety of concept drifts, novelty, evolving data, number and size of clusters and outlier detection are considered. Our algorithm is suitable for applications where the interest lies in the most recent information like stock market, or if the analysis of existing information is required as well as cases where both the old and the recent information are all equally important. The experiments, over the synthetic and real datasets, show that our proposed algorithm outperforms the other algorithms in efficiency. (C) 2019 Elsevier Ltd. All rights reserved.Article Citation - WoS: 17Citation - Scopus: 19Pro-Metastatic Functions of Notch Signaling Is Mediated by Cyr61 in Breast Cells(Elsevier, 2020) Küçükköse, Cansu; Efe, Eda; Günyüz, Zehra Elif; Fıratlıgil, Burcu; Doğan, Hülya; Yalçın Özuysal, Özden; İlhan, MustafaMetastasis is the main cause of cancer related deaths, and unfolding the molecular mechanisms underlying metastatic progression is critical for the development of novel therapeutic approaches. Notch is one of the key signaling pathways involved in breast tumorigenesis and metastasis. Notch activation induces pro-metastatic processes such as migration, invasion and epithelial to mesenchymal transition (EMT). However, molecular mediators working downstream of Notch in these processes are not fully elucidated. CYR61 is a secreted protein implicated in metastasis, and its inhibition by a monoclonal antibody suppresses metastasis in xenograft breast tumors, indicating the clinical importance of CYR61 targeting. Here, we aimed to investigate whether CYR61 works downstream of Notch in inducing pro-metastatic phenotypes in breast cells. We showed that CYR61 expression is positively regulated by Notch activity in breast cells. Notch1-induced migration, invasion and anchorage independent growth of a normal breast cell line, MCF10A, were abrogated by CYR61 silencing. Furthermore, upregulation of core EMT markers upon Notch1-activation was impaired in the absence of CYR61. However, reduced migration and invasion of highly metastatic cell line, MDA MB 231, cells upon Notch inhibition was not dependent on CYR61 downregulation. In conclusion, we showed that in normal breast cell line MCF10A, CYR61 is a mediator of Notch1-induced pro-metastatic phenotypes partly via induction of EMT. Our results imply CYR61 as a prominent therapeutic candidate for a subpopulation of breast tumors with high Notch activity.