1,720,955 research outputs found
UÇAK TAŞIMA YÜZEYLERİNDEKİ TRANSONİK AKIŞLARIN MAKİNA ÖĞRENİMİ İLE HESAPLANMASI
No full textThis study aims to reduce the computational cost of high-fidelity transonic flow simulations to the level of empirical tools using Machine-Learning methods. Therefore, high-fidelity wing optimizations and aeroelastic analyses of fighter aircraft can be affordable even in the conceptual design phase. The characteristics of pressure distributions over the various wing geometries are investigated. Deep neural networks having encoder-decoder architectures are created to model the wing pressure variation along chord and spanwise directions. The deep learning training is applied at Mach 0.9, and the angle of attack ranges between 7 and 12 degrees. Wing planform figures and low-fidelity datasets are the inputs of the deep learning algorithm. The low-fidelity dataset is created with 2D airfoil pressure distributions. The aspect ratio, leading-edge sweep, and taper ratio are represented in the wing planform figure. The airfoil characteristics, angle of attack, and tip twist are integrated as the low-fidelity dataset. distribution between the high and low fidelity dataset is the output of the deep learning model. A predictor algorithm is created to generate the high-fidelity pressure distributions using predictions. The size of training inputs, the number of feature maps, and interpolation performances are investigated. Pressure variations of different wing planforms are generated and compared. As the output of the thesis, the static pressure field on the suction and pressure sides of a fighter wing are accurately predicted with deep neural networks which are created by an encoder-decoder algorithm.Bu çalışma, yüksek sadakatli transonik akış simülasyonlarının hesaplama maliyetini, Makine Öğrenimi yöntemlerini kullanarak ampirik araçların düzeyine indirmeyi amaçlamaktadır. Bu sayede, savaş uçağı kanatlarının yüksek sadakatli optimizasyonları ve aeroelastik analizleri kavramsal tasarım aşamasında bile ekonomik hale gelebilir. Kanat yüzeylerindeki basınç dağılımının değişimi araştırılmış ve bu basınç dağılımını modellemek için kodlayıcı-kod çözücü yapısındaki derin sinir ağları oluşturulmuştur. Derin öğrenme eğitimi, Mach 0.9 hızında ve 7 ile 12 derece arasındaki hücum açıları aralığında uygulanmıştır. Kanat planform figürü ve düşük sadakatli veri setleri derin öğrenme algoritmasının girdileridir. Düşük sadakatli veri seti, 2 boyutlu kanat profili basınç dağılımları ile oluşturulmuştur. Kanat açıklık oranı, hücum kenar açısı ve koniklik oran parametreleri kanat planform figüründe temsil edilmiştir. Kanat profili özellikleri, hücum açısı ve uç burulma açısı düşük sadakatli veri setine entegre edilmiştir. Yüksek ve düşük sadakatli veri setleri arasındaki dağılımı derin öğrenme çıktısıdır. tahminleri kullanılarak yüksek sadakatli basınç dağılımlarını üretmek için bir tahminleyici algoritma oluşturulmuştur. Derin öğrenme eğitim setlerinin boyutu, filtre sayısı ve interpolasyon performansı araştırılmıştır. Farklı kanat planformlarının basınç dağılımları üretilmiş ve karşılaştırılmıştır. Tezin çıktısı olarak, kanadın üst ve alt yüzeylerindeki statik basınç alanı, kodlayıcı-kod çözücü yapısındaki derin sinir ağları ile yüksek hassasiyette tahmin edilmiştir.Ph.D. - Doctoral Progra
Darrieus tipi dikey eksenli rüzgar türbinlerinin performansının sayısal benzetimlerle tahmini.
No full textFlow over Darrieus type straight-bladed vertical axis wind turbines (VAWT) with NACA 0021 blade profile is simulated using ANSYS Fluent software. SST k- turbulence model is used for the two-dimensional, unsteady simulations. Wind speed is taken as 7 m/s and part of the problem domain including the rotating blades is modeled using the sliding mesh technique. Effects of boundary layer mesh parameters, time step and convergence tolerance on the solution accuracy are investigated with carefully designed runs. Performance of VAWTs with 2 and 3 blades, which are designed to have the same solidity ratio, are compared at different tip speed ratios. Instantaneous flow patterns of unsteady flow fields are analyzed by examining velocity and pressure contours. Start-up performance, which is known to be critical for Darrieus turbines, is investigated with special care and the effect of number of blades to this issue is studied.M.S. - Master of Scienc
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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