TR-Dizin İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/8652

Browse

Now showing 1 - 20 of 41

Adaptive Decision Fusion Based Framework for Short-Term Wind Speed and Turbulence Intensity Forecasting: Case Study for North West of Turkey
(2017) Toreyin, Behcet Ugur; Dinçkal, Çiğdem; Küçükali, Serhat
:In this paper, an online learning framework called adaptive decision fusion (ADF) is employed for short-term wind speed and turbulence intensity forecasting by use of wind speed data for each season for the city of ˙Izmit, located in the northwest of Turkey. Fixed-weight (FW) linear combination is derived and used for comparison with ADF. Wind speeds and turbulence intensities are predicted from the existing wind speed data and computed turbulence intensities, respectively, using the ADF and FW methods. Simulations are carried out for each season and the results are tested on mean absolute percentage error criterion. It is shown that the proposed model captured the system dynamic behavior and made accurate predictions based on the seasonal wind speed characteristics of the site. The procedure described here can be used to estimate the local velocity and turbulence intensity in a wind power plant during a storm.
Citation - WoS: 4
Citation - Scopus: 5
An Algebraic Stability Test for Fractional Order Time Delay Systems
(Ramazan Yaman, 2020) Baleanu, Dumitru; Ozyetkin, Munevver Mine
In this study, an algebraic stability test procedure is presented for fractionalorder time delay systems. This method is based on the principle of eliminatingtime delay. The stability test of fractional order systems cannot be examineddirectly using classical methods such as Routh-Hurwitz, because such systemsdo not have analytical solutions. When a system contains the square roots ofs, it is seen that there is a double value function of s. In this study, a stabilitytest procedure is applied to systems including ps and/or different fractionaldegrees such as s where 0 < α < 1, and αǫR. For this purpose, the integerorder equivalents of fractional order terms are first used and then the stabilitytest is applied to the system by eliminating time delay. Thanks to the proposedmethod , it is not necessary to use approximations instead of time delay termsuch as Pad´e. Thus, the stability test procedure does not require the solutionof higher order equations.
Citation - WoS: 2
Citation - Scopus: 3
Analysis of Mixed-Order Caputo Fractional System With Nonlocal Integral Boundary Condition
(Tubitak Scientific & Technological Research Council Turkey, 2018) Khodabakhshi, Neda; Baleanu, Dumitru; Akman Yildiz, Tugba
This paper deals with a mixed-order Caputo fractional system with nonlocal integral boundary conditions. This study can be considered as an extension of previous studies, since the orders of the equations lie on different intervals. We discuss the existence and uniqueness of the solution using fixed point methods. We enrich the study with an example.
Citation - WoS: 2
Citation - Scopus: 6
Barış Eğitimi: Evrimleşmiş bir Şiddetsizlik Bilinci için Eğitim
(Center Foreign Policy & Peace Research, 2016) Yemenici, Alev
Bu makale beyin temelli ön bir barış eğitimi modeli sunmayı amaçlamaktadır. Günümüzdeki barış eğitimi modellerinin vurguladığı insan hakları eğitimi, çevre eğitimi ve çatışma çözümü eğitimi konularının yanısıra, bu model şiddetin nörobiyolojik nedenleri ve erken önlenmesi meselelerinin ele alınabileceği yeni bir seviye -hücresel seviye- öne sürmektedir. Özellikle, bu model, şiddetin nörobiyolojik sebepleri ve önlenmesi ile erken travmanın doğum öncesi, doğum sırasında ve sonrasında gelişmekte olan beyin üzerindeki etkisi hakkındaki bilgileri yayılmasını savunmaktadır. Sevgi ve şiddete ilişkin kimyasallara dair temel ve beynin esas yapısı bu erken dönemlerde oluşmaktadır. Diğer bir deyişle bu model, çocuklar, ergenler ve yetişkinlerin eğitimi yoluyla şiddetin önlenebileceği hücresel bir boyut olduğunu ortaya koymaktadır.
Coset Algebras of the Maxwell-Einstein Supergravities
(Tubitak Scientific & Technological Research Council Turkey, 2006) Yılmaz, Nejat Tevfik
The general structure of the scalar cosets of the Maxwell-Einstein supergravities is given. Following an introduction of the non-linear coset formalism of the supergravity theories a comparison of the coset algebras of the Maxwell-Einstein supergravities in various dimensions is discussed.
Citation - WoS: 8
Citation - Scopus: 11
The Diagnosis of Femoroacetabular Impingement Can Be Made on Pelvis Radiographs Using Deep Learning Methods
(Turkish Joint Diseases Foundation, 2023) Atalar, Ebru; Ureten, Kemal; Kanatli, Ulunay; Ciceklidag, Murat; Kaya, Ibrahim; Vural, Abdurrahman; Maras, Yuksel
Objectives: The aim of this study was to evaluate diagnostic ability of deep learning models, particularly convolutional neural network models used for image classification, for femoroacetabular impingement (FAI) using hip radiographs. Materials and methods: Between January 2010 and December 2020, pelvic radiographs of a total of 516 patients (270 males, 246 females; mean age: 39.1 +/- 3.8 years; range, 20 to 78 years) with hip pain were retrospectively analyzed. Based on inclusion and exclusion criteria, a total of 888 hip radiographs (308 diagnosed with FAI and 508 considered normal) were evaluated using deep learning methods. Pre-trained VGG-16, ResNet-101, MobileNetV2, and Inceptionv3 models were used for transfer learning. Results: As assessed by performance measures such as accuracy, sensitivity, specificity, precision, F-1 score, and area under the curve (AUC), the VGG-16 model outperformed other pre-trained networks in diagnosing FAI. With the pre-trained VGG-16 model, the results showed 86.6% accuracy, 82.5% sensitivity, 89.6% specificity, 85.5% precision, 83.9% F1 score, and 0.92 AUC. Conclusion: In patients with suspected FAI, pelvic radiography is the first imaging method to be applied, and deep learning methods can help in the diagnosis of this syndrome.
Citation - WoS: 11
Citation - Scopus: 11
Diagnosis of Osteoarthritic Changes, Loss of Cervical Lordosis, and Disc Space Narrowing on Cervical Radiographs With Deep Learning Methods
(Turkish Joint Diseases Foundation, 2022) Tokdemir, Gul; Ureten, Kemal; Atalar, Ebru; Duran, Semra; Maras, Hakan; Maras, Yuksel
Objectives: In this study, we aimed to differentiate normal cervical graphs and graphs of diseases that cause mechanical neck pain by using deep convolutional neural networks (DCNN) technology. Materials and methods: In this retrospective study, the convolutional neural networks were used and transfer learning method was applied with the pre-trained VGG-16, VGG-19, Resnet-101, and DenseNet-201 networks. Our data set consisted of 161 normal lateral cervical radiographs and 170 lateral cervical radiographs with osteoarthritis and cervical degenerative disc disease. Results: We compared the performances of the classification models in terms of performance metrics such as accuracy,
Citation - WoS: 7
Citation - Scopus: 6
Dirac Systems With Regular and Singular Transmission Effects
(2017) Uğurlu, Ekin
In this paper, we investigate the spectral properties of singular eigenparameter dependent dissipative problems in Weyl s limit-circle case with finite transmission conditions. In particular, these transmission conditions are assumed to be regular and singular. To analyze these problems we construct suitable Hilbert spaces with special inner products and linear operators associated with these problems. Using the equivalence of the Lax Phillips scattering function and Sz-Nagy Foia¸s characteristic functions we prove that all root vectors of these dissipative operators are complete in Hilbert spaces.
Citation - WoS: 3
Citation - Scopus: 3
Dissipative Operator and Its Cayley Transform
(2017) Tas, Kenan; Uğurlu, Ekin
In this paper, we investigate the spectral properties of the maximal dissipative extension of the minimal symmetric differential operator generated by a second order differential expression and dissipative and eigenparameter dependent boundary conditions. For this purpose we use the characteristic function of the maximal dissipative operator and inverse operator. This investigation is done by the characteristic function of the Cayley transform of the maximal dissipative operator, which is a completely nonunitary contraction belonging to the class C0. Using Solomyak s method we also introduce the self-adjoint dilation of the maximal dissipative operator and incoming/outgoing eigenfunctions of the dilation. Moreover, we investigate other properties of the Cayley transform of the maximal dissipative operator.
Citation - WoS: 1
Citation - Scopus: 2
Effects of Routing Algorithms on Novel Throughput Improvement of Mobile Ad Hoc Networks
(2012) Preveze, Barbaros; Şafak, Aysel
A cognitive method called most congested access first (MCAF), minimizing the packet loss ratio and improving the throughput of a multihop mobile WiMAX network, is proposed. MCAF combines both the time division multiple access and the orthogonal frequency division multiple access methods. MCAF additionally uses spectral aid and buffer management methods, which are proposed in this paper, to manage both spectrum access and packets in the buffers. By using these novel methods, real-time video and voice packet transmission is achieved, data packet loss rate is minimized, and the system throughput per node is improved. Effects of fastest path and ant colony routing algorithms on throughput improvement methods are investigated. It is shown that the fastest path routing algorithm provides higher throughput values than the ant colony routing algorithm.
Citation - WoS: 7
Citation - Scopus: 10
Extending a Sentiment Lexicon With Synonym-Antonym Datasets: Swnettr Plus
(Tubitak Scientific & Technological Research Council Turkey, 2019) Genc, Burkay; Sever, Hayri; Saglam, Fatih
In our previous studies on developing a general-purpose Turkish sentiment lexicon, we constructed SWNetTR-PLUS, a sentiment lexicon of 37K words. In this paper, we show how to use Turkish synonym and antonym word pairs to extend SWNetTR-PLUS by almost 33% to obtain SWNetTR++, a Turkish sentiment lexicon of 49K words. The extension was done by transferring the problem into the graph domain, where nodes are words, and edges are synonym- antonym relations between words, and propagating the existing tone and polarity scores to the newly added words using an algorithm we have developed. We tested the existing and new lexicons using a manually labeled Turkish news media corpus of 500 news texts. The results show that our method yielded a significantly more accurate lexicon than SWNetTR-PLUS, resulting in an accuracy increase from 72.2% to 80.4%. At this level, we have now maximized the accuracy rates of translation-based sentiment analysis approaches, which first translate a Turkish text to English and then do the analysis using English sentiment lexicons.
Citation - WoS: 3
Citation - Scopus: 3
Filter Design for Small Target Detection on Infrared Imagery Using Normalized-Cross Layer
(Tubitak Scientific & Technological Research Council Turkey, 2020) Demir, H. Seckin; Akagunduz, Erdem
In this paper, we introduce a machine learning approach to the problem of infrared small target detection filter design. For this purpose, similar to a convolutional layer of a neural network, the normalized-cross-correlational (NCC) layer, which we utilize for designing a target detection/recognition filter bank, is proposed. By employing the NCC layer in a neural network structure, we introduce a framework, in which supervised training is used to calculate the optimal filter shape and the optimum number of filters required for a specific target detection/recognition task on infrared images. We also propose the mean-absolute-deviation NCC (MAD-NCC) layer, an efficient implementation of the proposed NCC layer, designed especially for FPGA systems, in which square root operations are avoided for real-time computation. As a case study we work on dim-target detection on midwave infrared imagery and obtain the filters that can discriminate a dim target from various types of background clutter, specific to our operational concept.
Citation - Scopus: 4
Finite Groups All Whose Abelian Subgroups of Equal Order Are Conjugate
(2006) Sezer, Sezgin; Waall, Robert W. Van Der
In this paper we classify the finite groups whose abelian subgroups of equal order (B*-groups) are conjugate. The classification has been achieved by means of a lot of general structure properties of B*-groups, provided in the course of the paper.
Citation - WoS: 7
Citation - Scopus: 7
Fourth Order Differential Operators With Distributional Potentials
(Tubitak Scientific & Technological Research Council Turkey, 2020) Bairamov, Elgiz; Ugurlu, Ekin
In this paper, regular and singular fourth order differential operators with distributional potentials are investigated. In particular, existence and uniqueness of solutions of the fourth order differential equations are proved, deficiency indices theory of the corresponding minimal symmetric operators are studied. These symmetric operators are considered as acting on the single and direct sum Hilbert spaces. The latter one consists of three Hilbert spaces such that a squarely integrable space and two spaces of complex numbers. Moreover all maximal self-adjoint, maximal dissipative and maximal accumulative extensions of the minimal symmetric operators including direct sum operators are given in the single and direct sum Hilbert spaces.
Citation - WoS: 6
Citation - Scopus: 8
General Formulation of the Scattered Matter Waves by a Quantum Shutter
(2009) Umul, Z. Yusuf
The scattering process of matter waves by a quantum shutter is investigated by using the spectrum integral representation. The scattered fields are expressed in terms of the Fresnel function. It is shown that the obtained equation gives the Moshinsky function for a one dimensional problem of the plane wave. Also a general integral representation is derived for two dimensional problems. The scattering of matter waves for some special wave-packets are examined analytically and numerically.
Citation - WoS: 13
Citation - Scopus: 15
Hardy-Copson Type Inequalities for Nabla Time Scale Calculus
(Tubitak Scientific & Technological Research Council Turkey, 2021) Kaymakcalan, Billur; Kayar, Zeynep
This paper is devoted to the nabla unification of the discrete and continuous Hardy?Copson type inequalities. Some of the obtained inequalities are nabla counterparts of their delta versions while the others are new even for the discrete, continuous, and delta cases. Moreover, these dynamic inequalities not only generalize and unify the related ones in the literature but also improve them in the special cases.
Citation - WoS: 1
Citation - Scopus: 3
Identifying Criminal Organizations From Their Social Network Structures
(Tubitak Scientific & Technological Research Council Turkey, 2019) Genc, Burkay; Sever, Hayri; Cinar, Muhammet Serkan
Identification of criminal structures within very large social networks is an essential security feat. By identifying such structures, it may be possible to track, neutralize, and terminate the corresponding criminal organizations before they act. We evaluate the effectiveness of three different methods for classifying an unknown network as terrorist, cocaine, or noncriminal. We consider three methods for the identification of network types: evaluating common social network analysis metrics, modeling with a decision tree, and network motif frequency analysis. The empirical results show that these three methods can provide significant improvements in distinguishing all three network types. We show that these methods are viable enough to be used as supporting evidence by security forces in their fight against criminal organizations operating on social networks.
İnşacılık, Kimlik, ‘Üretilmiş’ Vatandaşlar: Rusya’nın Abhazya ve Güney Osetya’da Vatandaşlık Politikaları
(2019) Ekinci, F. Didem
Mevcut çalışmada, devletçi/pragmatist ve medeniyetçi ekollerin etkili olduğu 1991 sonrası Rus dış politikasında önemini korumuş olan Yakın Çevre’de büyük güç kimliğiyle nüfuzu koruma hedefinin, bölgede bazı aktörlerle yerleşik kolektif kimliklerden faydalanarak vatandaşlık verme politikasıyla pekiştirildiği İnşacı perspektiften tartışılmaktadır. Rusya’nın, kadim büyük güç kimlik algısı üzerinden eski kolektif kimlikler aracılığıyla bazı halklara vatandaşlık vermesi, yeni icat edilmiş ve geçici bir politika olmayıp, köklerinin Çarlık döneminden bu yana gözlemlenebilen nüfuz amaçlı tabiiyet/vatandaşlık politikalarını yansıtması; Yakın Çevre’nin Rusya açısından vazgeçilmez bir bölge olduğu ile gelecekte uygulamayı başka Yakın Çevre aktörleriyle de gerçekleştirebileceği savını güçlendirmektedir.
ISAR Imaging of Drone Swarms at 77 GHz
(TÜBİTAK Scientific & Technological Research Council of Turkey, 2025) Coruk, Remziye Busra; Kara, Ali; Aydin, Elif
The proliferation of easily available, internet-purchased drones, coupled with the emergence of coordinated drone swarms, poses a significant security threat for airspace. Detecting these swarms is crucial to prevent potential accidents, criminal misuse, and airspace disruptions. This paper proposes a novel inverse synthetic aperture radar (ISAR) imaging technique for high-resolution reconstruction of drone swarms at 77 GHz millimeter wave (mmWave) frequency, offering a valuable tool for military and defense antidrone systems. The key parameters affecting down-range and cross-range resolution (0.05 m), ultimately enabling the generation of detailed ISAR images are discussed. Here, we create diverse scenarios encompassing various swarm formations, sizes, and payload configurations by employing ANSYS simulations. To enhance image quality, different window functions are evaluated, and the Hamming window is selected due to its highest peak signal-to-noise ratio (PSNR) (16.3645) and structural similarity (SSIM) (0.9067) values, ensuring superior noise reduction and structural preservation. The results demonstrate that the effectiveness of high-resolution ISAR imaging in accurately detecting and characterizing drone swarms pave the way for enhanced airspace security measures.
Citation - WoS: 3
Citation - Scopus: 3
The Lebesgue Constants on Projective Spaces
(2021) Kushpel, Alexander
We give the solution of a classical problem of Approximation Theory on sharp asymptotic of the Lebesgueconstants or norms of the Fourier-Laplace projections on the real projective spaces Pd(R). In particular, these resultsextend sharp asymptotic found by Fejer [2] in the case of S1in 1910 and by Gronwall [4] in 1914 in the case of S2. Thecase of spheres, Sd, complex and quaternionic projective spaces, Pd(C), Pd(H) and the Cayley elliptic plane P16(Cay)was considered by Kushpel [8].

Browse

Browsing TR-Dizin İndeksli Yayınlar Koleksiyonu by Scopus Q "Q2"