TR-Dizin İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://gcris.khas.edu.tr/handle/20.500.12469/4467

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Citation Count: 2
3D self-assemble formation of molybdenum disulfide (MoS2)-doped polyacrylamide (PAAm) composite hydrogels
(Tubitak Scientific & Technological Research Council Turkey, 2022) Durmaz, Sumeyye; Yildiz, Ekrem; Uysal, Bengu Ozugur; Pekcan, Onder
Polyacrylamide (PAAm), a renowned member of the hydrogel class, has many uses throughout a wide range of industrial processes, including water absorbed diapers, contact lenses, wastewater treatment, biomedical applications such as drug delivery vehicles and tissue engineering because of its physical stability, durability, flexibility easier shaping, and so on. PAAm also provides new functionalities after the incorporation of inorganic structures such as molybdenum disulfide (MoS2). During the copolymerization process, the transmittance of all samples reduced significantly after a particular time, referred to as the gel point. Microgels form a tree above the gel point as projected by Flory-Stockmayer classical theory. Because of microgels positioned at the junction points of the Cayley tree, the addition of MoS2 results in strong intramolecular crosslinking and looser composites. Moreover, fractal geometry provides a quantitative measure of randomness and thus permits characterization of random systems such as polymers. Fractal dimension of these polymer composites is calculated from power-law-dependent scattered intensity. It was also confirmed that a hydrogel rapidly formed within a few seconds, indicating a 3D network formation inside the gel. These materials may have a great potential for application in wearable and implantable electronics due to this highly desired 3D self-assemble feature.
Citation Count: 4
Accurate indoor positioning with ultra-wide band sensors
(Tubitak, 2020) Arsan, Taner
Ultra-wide band is one of the emerging indoor positioning technologies. In the application phase, accuracy and interference are important criteria of indoor positioning systems. Not only the method used in positioning, but also the algorithms used in improving the accuracy is a key factor. In this paper, we tried to eliminate the effects of off-set and noise in the data of the ultra-wide band sensor-based indoor positioning system. For this purpose, optimization algorithms and filters have been applied to the raw data, and the accuracy has been improved. A test bed with the dimensions of 7.35 m x 5.41 m and 50 cm x 50 cm grids has been selected, and a total of 27,000 measurements have been collected from 180 test points. The average positioning error of this test bed is calculated as 16.34 cm. Then, several combinations of algorithms are applied to raw data. The combination of Big Bang-Big Crunch algorithm for optimization, and then the Kalman Filter have yielded the most accurate results. Briefly, the average positioning error has been reduced from 16.34 cm to 7.43 cm.
Citation Count: 0
Açık kalp cerrahisi sonrası vertebral osteomiyelit mediastinitin önemli bir komplikasyonu
(2001) Güden, Mustafa; Akpınar, Belhan; Sağbaş, Ertan; Sanisoğlu, İlhan; Şirvancı, Mustafa; Bayramoğlu, Zehra; Çaynak, Barış; Yüksel, Alper
[Abstract Not Available]
Citation Count: 0
Aortanın ileri derecede aterosklerozunda koroner arter cerrahisi
(1999) Akpınar, Belhhan; Güden, Mustafa; Polat, Bülent; Sağbaş, Ertan; Sanisoğlu, İlhan; Sönmez, Bingür; Demiroğlu, Cemşid
Açık kalp cerrahisinde tekniklerin ilerlemesine rağmen nörolojik komplikasyonların görülme sıklığı azalmamıştır ve inme (stroke) morbidite ve mortaliteyi önemli ölçüde artırmaktadır. Bu yazıda çıkan aortada ileri derecede kalsifikasyon bulunan vakalarda hipotermik fibrilasyon tekniği kullanılarak aortaya dokunulmadan ve kross klemp konulmadan yapılan koroner by-pass ameliyatları anlatıldı. 2 yıl içinde aortada ileri derecede kalsifikasyon bulunan 23 olguda bu teknik kullanıldı. Yaş ortalaması 65 + 3 yıl idi. Kardiopulmoner bypass için femoral arter ve sağ atrium kullanıldı. Tüm hastalar 26-28 ºC'de ventriküler fibrilasyon ile ameliyat edildi ve internal torasik arterler ve gastroepiploik arter ve bu greftlerin kombinasyonu kullanıldı. Aortaya klemp uygulanmadı ve proksimal anastomoz yapılmadı. 30 günlük ölüm oranı 0 idi. Hiçbir olguda nörolojik komplikasyon, alt ekstremite iskemisi ve hemodinamik problem gözlenmedi. Sadece 1 olgu kanama nedeniyle tekrar ameliyata alındı ve eksik revaskülarizasyon yapılan 1 vakada peroperatif miyokard enfarktüsü görüldü, fakat hemodinamik olarak bir problem olmadı. Bu teknik iyi miyokard korunması sağladığı, uygun revaskülarizasyonu engellemediği ve emboliye bağlı nörolojik komplikasyonları önemli ölçüde engellediği için tercih edilebilir.
Citation Count: 1
Bayesian estimation of discrete-time cellular neural network coefficients
(TUBITAK Scientific & Technical Research Council Turkey, 2017) Şenol, Habib; Özmen, Atilla; Şenol, Habib
A new method for finding the network coefficients of a discrete-time cellular neural network (DTCNN) is proposed. This new method uses a probabilistic approach that itself uses Bayesian learning to estimate the network coefficients. A posterior probability density function (PDF) is composed using the likelihood and prior PDFs derived from the system model and prior information respectively. This posterior PDF is used to draw samples with the help of the Metropolis algorithm a special case of the Metropolis--Hastings algorithm where the proposal distribution function is symmetric and resulting samples are then averaged to find the minimum mean square error (MMSE) estimate of the network coefficients. A couple of image processing applications are performed using these estimated parameters and the results are compared with those of some well-known methods.
Citation Count: 1
COVID-19 modeling based on real geographic and population data
(Tubitak Scientific & Technological Research Council Turkey, 2023) Baysazan, Emir; Berker, A. Nihat; Mandal, Hasan; Kaygusuz, Hakan
Background/aim: Intercity travel is one of the most important parameters for combating a pandemic. The ongoing COVID-19 pandemic has resulted in different computational studies involving intercity connections. In this study, the effects of intercity connections during an epidemic such as COVID-19 are evaluated using a new network model. Materials and methods: This model considers the actual geographic neighborhood and population density data. This new model is applied to actual Turkish data by means of provincial connections and populations. A Monte Carlo algorithm with a hybrid lattice model is applied to a lattice with 8802 data points. Results: Around Monte Carlo step 70, the number of active cases in Turkiye reaches up to 8.0% of the total population, which is followed by a second wave at around Monte Carlo step 100. The number of active cases vanishes around Monte Carlo step 160. Starting with Istanbul, the epidemic quickly expands between steps 60 and 100. Simulation results fit the actual mortality data in Turkiye. Conclusion: This model is quantitatively very efficient in modeling real-world COVID-19 epidemic data based on populations and geographical intercity connections, by means of estimating the number of deaths, disease spread, and epidemic termination.
Citation Count: 3
Deniz dibi tarama malzemesi, kömür uçucu külü ve atık döküm kumunun hafif agrega olarak geri kazanımı
(2019) Erdoğan, Pembe Özer; Başar, Hatice Merve
Günümüzde, yüksek miktardaki deniz dibi tarama malzemesinin (DTM) diğer endüstriyel atıklarla birliktesürdürülebilir çevresel yönetimi Türkiye genelinde ortak bir sorundur. DTM ve atıkların denizeboşaltım/bertaraf yerine yapay hafif (kaba) agrega (YHA) üretiminde hammadde olarak faydalıkullanımı/geri kazanımı, döngüsel ekonomi kapsamında önemli çevresel kazanç sağlayacaktır. Buçalışmada, DTM, kömür uçucu külü ve atık döküm kumu kullanılarak YHA üretimi araştırılmıştır.Hammaddelerin üç farklı karışımı pelletleme diskinde granüle edilmiş, 105ºC’de kurutulmuş ve kül fırınında1100, 1150, 1170, 1180 ve 1190°C’de 5-10°C/min ısıtma hızı ve 10-20 min sinterleme süresindesinterlenmiştir. Sinterlenen YHA’lar fiziksel, mekanik, mikroyapısal, mineralojik ve sızma özellikleriaçısından analiz edilmiştir. 1190°C sinterleme sıcaklığı, 5°C/min ısıtma hızı ve 20 min sinterleme süresindeüretilen YHA’lar daha iyi agrega özelliklerine neden olmuştur. Ayrıca, bu agregaların sızma (liç) testisonuçlarına göre; eluat ve original atık parametrelerinin, sinterleme prosesinde silika matriksine hapsolmasınedeni ile III. Sınıf (İnert Atık) düzenli depolama tesisi limit değerlerinin altında olduğu; böylece, yapısektöründe kullanım için çevresel risk teşkil etmediği görülmüştür.
Citation Count: 4
Development of a supervised classification method to construct 2D mineral maps on backscattered electron images
(Tubitak, 2020) Çavur, Mahmut; Çavur, Mahmut
The Mineral Liberation Analyzer (MLA) can be used to obtain mineral maps from backscattered electron (BSE) images of particles. This paper proposes an alternative methodology that includes random forest classification, a prospective machine learning algorithm, to develop mineral maps from BSE images. The results show that the overall accuracy and kappa statistic of the proposed method are 97% and 0.94, respectively, proving that random forest classification is accurate. The accuracy indicators also suggest that the proposed method may be applied to classify minerals with similar appearances under BSE imaging. Meanwhile, random forest predicts fewer middling particles with binary and ternary composition, but the MLA predicts more middling particles only with ternary composition. These discrepancies may arise because the MLA, unlike random forest, may also measure the elemental compositions of mineral surfaces below the polished section.
Citation Count: 2
Distribution of HLA epitope frequencies in Turkish population
(Walter De Gruyter Gmbh, 2022) Oguz, Fatma Savran; Oguz, Suleyman Rustu; Ogret, Yeliz; Karadeniz, Tanju Sedat; Ciftci, Hayriye Senturk; Karatas, Sule; Kivanc, Demet
Objectives The antibodies interact with the Human Leukocyte Antigen (HLA) antigens at specific epitopes. Epitopes are present on a single HLA or shared by multiple antigens. In this study, we aim to determine the frequency of prevalent epitopes common in the Turkish population. Methods Non-related 644 healthy volunteers were recruited, and The HLA-A, -B, -C, -DR -DQ's were typed using the Next Generation Sequencing. The provisional and confirmed epitopes were identified using the HLA Epitope Registry databases, HLA Epitopia Maps and Immucor Epitope databases dated 07.02.2018. Epitope frequencies were calculated by counting the shared epitopes in the total number of shared HLA Class epitopes in our sample database. Results Class I HLA's had 298 epitopes that repeated a total of 158,117 times with frequencies ranging between 0.0006 and 2.03%, and the most frequent epitope was 170RY found on 119 different alleles. Class II HLA's had 193 epitopes that repeated a total of 93,082 times with frequencies ranging between 0.002 and 1.36%, and the most frequent epitope was 108P found on 42 different alleles. Conclusions Our findings summarize both the provisional, and confirmed epitope frequencies in the Turkish population and may help clinicians and immunogeneticists develop a better understanding of HLA epitope mismatches.
Citation Count: 0
Drıvers of Employee Dis/Satisfaction: A Comparison of Tourism and Sports Industries
(Akdeniz Univ, Tourism Fac, 2023) Kozak, Metin; Kozak, Metin; Oezdemir, Ilknur
This study aims to identify the common and distinct factors affecting the dis/satisfaction of employees in two different industries, namely tourism and sports, and develop a model. The study was carried out using the qualitative method. A total of 118 employees in five-star hotels and sports centers participated in the study. Common factors affecting employee satisfaction were thematized as relationship with co-workers, nature of the job, relationship with superiors, salary, working hours, career opportunities, and job security. The factors affecting the dissatisfaction were thematized as inefficient salary, lack of relationship with superiors, job insecurity, and lack of relationship with co-workers. In the context of satisfaction in tourism, the theme of Facilities and benefits differs from sports. In the context of dissatisfaction with sports, the theme of lack of career opportunities differs from tourism. Based on the study findings, practical implications are presented for the two industries in an aim to increase the performance and productivity of their businesses. The study conveys its originality by identifying the employee dis/satisfaction factors in the tourism and sports industries.
Citation Count: 0
Drivers of Employee Dis/Satisfaction: A Comparison of Tourism and Sports Industries
(2023) Kozak, Metin; Kozak, Metin; Özdemir, İlknur
This study aims to identify the common and distinct factors affecting the dis/satisfaction of employees in two different industries, namely tourism and sports, and develop a model. The study was carried out using the qualitative method. A total of 118 employees in five-star hotels and sports centers participated in the study. Common factors affecting employee satisfaction were thematized as relationship with co-workers, nature of the job, relationship with superiors, salary, working hours, career opportunities, and job security. The factors affecting the dissatisfaction were thematized as inefficient salary, lack of relationship with superiors, job insecurity, and lack of relationship with co-workers. In the context of satisfaction in tourism, the theme of “Facilities and benefits” differs from sports. In the context of dissatisfaction with sports, the theme of “lack of career opportunities” differs from tourism. Based on the study findings, practical implications are presented for the two industries in an aim to increase the performance and productivity of their businesses. The study conveys its originality by identifying the employee dis/satisfaction factors in the tourism and sports industries.
Citation Count: 3
E-İşte Sürdürülebilir Bağlantılığı İzlemek için Ağ Tabanlı Teorinin Kullanımı
(Turkish Journal of Electrical Engineering and Computer Sciences, 2020) Çavur, Mahmut; Çavur, Mahmut
The Mineral Liberation Analyzer (MLA) can be used to obtain mineral maps from backscattered electron (BSE) images of particles. This paper proposes an alternative methodology that includes random forest classification, a prospective machine learning algorithm, to develop mineral maps from BSE images. The results show that the overall accuracy and kappa statistic of the proposed method are 97% and 0.94, respectively, proving that random forest classification is accurate. The accuracy indicators also suggest that the proposed method may be applied to classify minerals with similar appearances under BSE imaging. Meanwhile, random forest predicts fewer middling particles with binary and ternary composition, but the MLA predicts more middling particles only with ternary composition. These discrepancies may arise because the MLA, unlike random forest, may also measure the elemental compositions of mineral surfaces below the polished section.
Citation Count: 6
Fault tolerant control with re-configuring sliding-mode schemes
(2005) Kerestecioğlu, Feza; Kerestecioğlu, Feza
In this paper a controller design method for linear MIMO systems is presented which a sliding mode controller is reconfigured in case of system faults. Faults are detected with the residual vector generated from a standard linear observer. Once a fault has been detected the fault distribution matrix can be obtained and used to update the corrective or equivalent control parts of the sliding mode controller. As a result fault tolerant adaptive controllers keep the system performance within acceptable limits or at least avoids the system to wind-up. © TÜBITAK.
Femoral arteriyovenöz fistülün endovasküler stent greft ile perkütan tedavisi: Olgu sunumu
(Bayçınar Tıbbi Yayıncılık, 2003) Onat, Levent; Karaman, Kutlay; Şırvancı, Mustafa; Aydıner, Ömer; Olga, Rüstem
Karotis endarterektomi ve koroner bypass ameliyatları planlanan 65 yaşında erkek hastanın sağ femoral bölgesinde tril ve üfürüm mevcuttu. Yapılan manyetik rezonans anjiyografi incelemesinde sağ femoral arteriyovenöz fistül ve sol renal arterde stenoz saptandı. Ameliyat öncesi ilk seansta renal arter darlığı endovasküler stent uygulanarak giderildi. İkinci seansta sol femoral yol ile sağ femoral artere stent greft yerleştirildi. Yapılan kontrol enjeksiyonda fistülün büyük ölçüde, bir sonraki gün yapılan manyetik rezonans anjiyografide ve Doppler incelemesinde tamamen kapandığı görüldü.
Citation Count: 1
Filtre modelli öznitelik seçim algoritmalarının EEG tabanlı beyin bilgisayar arayüzü sistemindeki karşılaştırmalı sınıflandırma performansları
(2023) Ballı, Tuğçe; Ballı, Tuğçe; Yetkin, E. Fatih
Beyin bilgisayar arayüzleri (BBA), beyin elektriksel aktivitelerini kontrol komutlarına çevirerek bilgisayar veya nöroprostetik kol gibi yardımcı teknolojilerin kullanılmasını sağlayan sistemlerdir. Bu çalışmada filtre tabanlı öznitelik seçim yöntemlerinin farklı sınıflandırma algoritmaları ile birlikte kullanılmasının BBA sistemlerine getirebileceği kazanımlar araştırılmıştır. Bu çerçevede nöroprostetik bir cihazın kontrolü için tasarlanan BBA sisteminden elde edilmiş EEG kayıtları analiz edilmiştir. EEG kayıtlarının analizi için delta (1.0-4 Hz), teta (4-8 Hz), alfa (8-12 Hz), beta (12-25 Hz), yüksek-beta (25-30Hz) ve gama (30-50 Hz) frekans bantlarından ve delta (1-4 Hz), teta (4-8 Hz), alfa1 (8-10 Hz), alfa2 (10-12 Hz), beta1 (12-15 Hz), beta2 (15-18 Hz), beta3 (18-25 Hz), gama1 (30-35 Hz), gama2 (35-40 Hz), gama3 (40-50 Hz) alt frekans bantlarından bant gücü öznitelikleri çıkarılmıştır. Elde edilen iki veri seti öznitelik seçimi uygulamadan ve öznitelik seçimi uygulayarak sınıflandırılmıştır. Çalışmada toplam 10 adet filtre tabanlı öznitelik seçimi yöntemi ile birlikte, doğrusal ayırt eden analizi, rassal ormanlar, karar ağaçları ve destek vektör makinaları sınıflandırma algoritmaları kullanılmıştır. Çalışma sonucunda EEG kayıtlarının sınıflandırılması için öznitelik seçme algoritmalarının uygulanmasının daha yüksek başarımlı sonuçlar verdiği ve bu çalışmada ele alınan öznitelik seçme yöntemlerinden, özdeğer merkeziyetine göre öznitelik seçimi (Ecfs) ve sonsuz öznitelik seçimi (Inffs) yöntemlerinin filtre tabanlı yaklaşımlar arasında en iyi sonuçları verdiği gözlenmiştir.
Citation Count: 6
Foster impedance data modeling via singly terminated LC ladder networks
(TUBITAK Scientific & Technical Research Council Turkey, 2013) Şengül, Metin Y.
In this work a lossless model is developed for the given Foster impedance data. In the model a 2-port short-or open-terminated LC ladder is used. After applying the proposed algorithm a realizable driving-point reactance function that fits the given data is obtained. Next this function is synthesized resulting in the desired model. In the algorithm there is no need to select a circuit topology for the model. Two examples are given to illustrate the utilization of the proposed modeling algorithm.
Citation Count: 0
Grammatical Complexity and Gesture Production of Younger and Older Adults;
(Dilbilim Dernegi, 2023) Özer, Demet; Özer,D.; Göksun,T.
Age-related effects are observed in both speech and gesture production. Older adults produce grammatically fewer complex sentences and use fewer iconic gestures than younger adults. This study investigated whether gesture use, especially iconic gesture production, was associated with the syntactic complexity within and across younger and older age groups. We elicited language samples from these groups, using a picture description task (N=60). Results suggested shorter and less complex speech for older than younger adults. Although the two age groups were similar in overall gesture frequency, older adults produced fewer iconic gestures. Overall gesture frequency, along with participants’ ages, negatively predicted grammatical complexity. However, iconic gesture frequency was not a significant predictor of complex syntax. We conclude that each gesture might carry a function in a coordinated multimodal system, which might, in turn, influence speech quality. Focusing on individual differences, rather than age groups, might unravel the nature of multimodal communication. © 2023 Dilbilim Derneği, Ankara.
Citation Count: 0
Güç akışı analizinin geçici hata duyarlılığının değerlendirilmesi
(2023) Yetkin, Emrullah Fatih
Günümüzün güç sistemleri detaylı modelleme ihtiyaçları nedeniyle çok büyük boyutlara ulaşabilmektedir ve belirli koşullar için sistemin tek bir anlık görüntüsünün çözümü bile büyük boyutlu denklem sistemlerinin çözümünü gerektirir. Bu nedenle de makul bir sürede sonuçları elde etmek için modern yüksek başarımlı hesaplama ortamları kullanılmalıdır. Bununla birlikte, yüksek başarımlı hesaplama ortamlarında artan bileşen sayısı nedeniyle, geçici hata olasılığı da artar. Geçici hatalar, x-ışınları, kozmik parçacık etkileri gibi nedenlerle cihaz bileşenlerinde oluşabilen çeşitli dalgalanmalardan kaynaklı arızalar olarak tanımlanabilir. Bu tür hatalar genellikle herhangi bir hesaplama anında herhangi bir kayan nokta işleminde yaşanan bir bit- kayması ile modellenebilir. Bu makalede, büyük ölçekli güç akışı simülasyonları üzerindeki geçici hata etkileri incelenmektedir. Genel olarak yük akışı hesaplamaları, sistem doğrusal olmayan denklemlerle modellendiği için, Newton-Raphson yöntemi kullanılarak yapılır ve çözüm süreci, her yinelemede Jakobiyen matrisinin tersini almak için doğrusal bir çözücünün kullanılmasını gerektirir. Bu çalışmada, özellikle yenilenebilir enerji kaynaklarının sistemlere eklenmesi ile çok büyük boyutlara ulaşılabilen elektrik yük akış problemlerinde kullanılan matematiksel yöntemlerin geçici-hatalara karşı hassasiyetleri incelenerek, karşılaşılabilecek sorunlar ortaya konulmuştur.
Citation Count: 1
Haydarpasa Train Station: Present Past And Future
(Middle East Technical Univ, 2013) Erkan Kösebay, Yonca
The facade of Haydarpasa Train Station has been changed more than once in the course of its century old life time. Until the fire in November 2010 wiping out the roof the building was recalled only with a single image although the original facade of the building was slightly different than it is commonly remembered one. Currently while the wounds of the building are on the verge of healing a new identity for the station is being tailored
Citation Count: 0
Haydarpaşa Tren Garı: Bugün, Dün ve Yarın (1) Kentin Bedeninde Bir Yara (2)
(2013) Erkan, Yonca Kösebay
[Abstract Not Available]

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