Browsing by Subject "Multi-task learning"

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    ItemOpen Access
    Çok görevli öğrenme ile eşzamanlı darbe tespiti ve kipleme sınıflandırma
    (IEEE, 2019-04) Akyön, Fatih Çağatay; Nuhoğlu, Mustafa Atahan; Alp, Yaşar Kemal; Arıkan, Orhan
    Bu çalışmada, elektronik harp sistemlerindeki sayısal almaç yapıları tarafından toplanan, ortamdaki tehdit radarların gönderdigi darbesel sinyal örnekleri üzerinden otomatik olarak eşzamanlı SGO (Sinyal Gürültü Oranı) kestiren ve darbe tespiti yapan, tespit edilen darbesel bölge üzerindeki kiplemeyi sınıflandıran, çok görevli ögrenme ve yinelemeli sinir ağı tabanlı yeni bir yöntem önerilmiştir. Önerilen yöntem, girdi olarak almaç tarafından toplanan örneklerden herhangi bir öznitelik çıkarmaksızın, ham IQ (Inphase-Quadrature) verilerini kullanmaktadır. Sınıflandırma başarımını artırmak için, farklı SGO seviyelerine göre eğitilmiş modeller kullanılmıştır. Ham IQ veri üzerinden kestirilen SGO degerine göre, uygun model otomatik olarak seçilmektedir. Yapılan kapsamlı benzetimlerde, -30 dB SGO seviyesinde, 1.5 dB ortalama mutlak hata ile SGO kestirimi, %90 başarımla darbe tespiti ve %84 ihtimalle başarılı kipleme sınıflandırması yapılabildiği gözlemlenmiştir. Tipik bir elektronik ˘ harp almacının darbe tespiti yapabildigi en dü¸sük SGO seviyesinin 10 dB olduğu düşünüldüğünde, önerilen yöntemin geleceğin elektronik harp almaç yapıları için oldukça önemli bir teknolojik kazanım olduğu değerlendirilmektedir.
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    DeepDistance: a multi-task deep regression model for cell detection in inverted microscopy images
    (Elsevier, 2020) Koyuncu, Can Fahrettin; Güneşli, Gözde Nur; Çetin-Atalay, Rengül; Gündüz-Demir, Çigdem
    This paper presents a new deep regression model, which we call DeepDistance, for cell detection in images acquired with inverted microscopy. This model considers cell detection as a task of finding most probable locations that suggest cell centers in an image. It represents this main task with a regression task of learning an inner distance metric. However, different than the previously reported regression based methods, the DeepDistance model proposes to approach its learning as a multi-task regression problem where multiple tasks are learned by using shared feature representations. To this end, it defines a secondary metric, normalized outer distance, to represent a different aspect of the problem and proposes to define its learning as complementary to the main cell detection task. In order to learn these two complementary tasks more effectively, the DeepDistance model designs a fully convolutional network (FCN) with a shared encoder path and end-to-end trains this FCN to concurrently learn the tasks in parallel. For further performance improvement on the main task, this paper also presents an extended version of the DeepDistance model that includes an auxiliary classification task and learns it in parallel to the two regression tasks by also sharing feature representations with them. DeepDistance uses the inner distances estimated by these FCNs in a detection algorithm to locate individual cells in a given image. In addition to this detection algorithm, this paper also suggests a cell segmentation algorithm that employs the estimated maps to find cell boundaries. Our experiments on three different human cell lines reveal that the proposed multi-task learning models, the DeepDistance model and its extended version, successfully identify the locations of cell as well as delineate their boundaries, even for the cell line that was not used in training, and improve the results of its counterparts.
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    Multi-task network for computed tomography segmentation through fractal dimension estimation
    (2023-01) Jabdaragh, Aziza Saber
    Multi-task learning proved to be an effective strategy to increase the performance of a dense prediction network on a segmentation task, by defining auxiliary tasks to reflect different aspects of the problem and concurrently learning them with the main task of segmentation. Up to now, previous studies defined their auxiliary tasks in the Euclidean space. However, for some segmentation tasks, the complexity and high variation in the texture of a region of interest may not follow the smoothness constraint in the Euclidean geometry. This thesis addresses this issue by introducing a new multi-task network, MTFD-Net, which utilizes the fractal geometry to quantify texture complexity through self-similar patterns in an image. To this end, we propose to transform an image into a map of fractal dimensions and define its learning as an auxiliary task, which will provide auxiliary supervision to the main segmentation task, towards betterment of left atrium segmentation in computed tomography images. To the best of our knowledge, this is the first proposal of a dense prediction network that employs the fractal geometry to define an auxiliary task and learns it in parallel to the segmentation task in a multi-task learning framework. Our experiments revealed that the proposed MTFD-Net model led to more accurate left atrium segmentation, compared to its counterparts.
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    xDBTagger: explainable natural language interface to databases using keyword mappings and schema graph
    (Springer, 2023-08-23) Usta, A.; Karakayalı, A.; Ulusoy, Özgür
    Recently, numerous studies have been proposed to attack the natural language interfaces to data-bases (NLIDB) problem by researchers either as a conventional pipeline-based or an end-to-end deep-learning-based solution. Although each approach has its own advantages and drawbacks, regardless of the approach preferred, both approaches exhibit black-box nature, which makes it difficult for potential users to comprehend the rationale behind the decisions made by the intelligent system to produce the translated SQL. Given that NLIDB targets users with little to no technical background, having interpretable and explainable solutions becomes crucial, which has been overlooked in the recent studies. To this end, we propose xDBTagger, an explainable hybrid translation pipeline that explains the decisions made along the way to the user both textually and visually. We also evaluate xDBTagger quantitatively in three real-world relational databases. The evaluation results indicate that in addition to being lightweight, fast, and fully explainable, xDBTagger is also competitive in terms of translation accuracy compared to both pipeline-based and end-to-end deep learning approaches.