Develi, Ahmet Çağrı | Olcay, Ali Bahadır

Article | 2017 | Sakarya Üniversitesi Fen Bilimleri Enstitüsü Dergisi21 ( 5 ) , pp.1081 - 1087

There have been developments on surface texturing methods providing benefit in a great many engineering applications.Especially, influence on surface texturing in lubrication applications related to frictional properties have been cause of concern.In the present study, it was aimed to work on the computational fluid dynamics (CFD) study of the lubrication system consistingof two parallel plates. While one of the plates was sliding, the other one was stationary and an incompressible two-dimensionalsingle phase flow was assumed between those plates. The scope of the CFD analysis was to determine the relationship betweendrag force and . . .operating fluid properties (i.e., oil types), rotational speed and the amount of the cavities. It was realized that SAE0W-30 was found to be the best fluid among the seven studied oil types providing optimal conditions such as high drag reductionand less drag force. It was noticed that the drag coefficient thus, drag force appeared to be increasing as the rotating disk speedrose. The influence of the number of the cavities along the textured surface was also investigated in the present study and it wasfound that drag reduction was not associated with the number of cavities because 0, 1, 2 and 3 cavities nearly gave the same dragforce values. Yüzey dokusu yöntemlerinde gelişmeler yaşanırken bu gelişmelerden birçok mühendislik uygulamaları fayda sağlayabilir.Özellikle sürtünme özellikleri ile ilgili yağlama uygulamalarında yüzey dokusu etkisi önemli bir etkiye sahiptir. Bu çalışmakapsamında iki paralel plakadan oluşan yağlama sisteminin hesaplamalı akışkanlar dinamiği çalışmasıyla incelenmesihedeflenmiştir. Plakalardan birisi hareket ederken, diğer plaka sabittir ve plakalar arasındaki akış, sıkıştırılamaz, iki boyutlu vetek fazlı olarak kabul edildi. Hesaplamalı akışkanlar dinamiği analizinin amacı direnç kuvvetindeki azalmanın, çalışan akışkanözellikleri (yani yağ çeşidi), açısal hız ve boşluk miktarı ile nasıl ilişkili olduğunu belirlemektir. Bu çalışmada SAE 0W-30 tipiyağın, çalışılan yedi yağ arasında en yüksek direnç düşüşü ve daha az direnç kuvveti sağladığı için en uygun koşulları sağlayanakışkan olduğu belirlenmiştir. Direnç katsayısının ve dolayısıyla direnç kuvvetinin açısal hızın artmasıyla arttığı fark edilmiştir.Boşluk sayısının yüzey dokusuna etkisi de bu çalışma kapsamında araştırılmıştır ve dirençteki azalmanın boşluk sayısı ile ilişkiliolmadığı bulunmuştur. Bunun nedeni 0, 1, 2 ve 3 boşluk yerleştirildiğinde neredeyse aynı direnç kuvvetleri elde edilmiştir Daha fazlası Daha az

Utku, Feride Sermin | Basaran, Kubra | Sunar, Yagmur | Celebıoglu, Hulya | Kapıcı, Ibrahim

Article | 2017 | Istanbul University Journal of Electrical and Electronics Engineering17 ( 2 ) , pp.3439 - 3443

Mineralized natural protein based novel bone replacement materials are investigated for tissue engineering. Mineralized silk fibroin composite foams and films display excellent biocompatibility. In this study, the biomimetic and electrochemical mineralization of orderly oriented silk fibroin scaffolds was studied. Commercially obtained pure silk woven fabric was boiled in 0.02 M Na2CO3 for 20 min. Calcium phosphate was deposited at 37°C for twenty minutes in seven sequential immersion steps, using 250 mM CaCl2 2H2O and 120 mM K2HPO4, containing 0.15 M NaCl and 50mM TRIS-HCl, pH 7.4, followed by electrochemical treatment in modif . . .ied SBF solution at 40°C at a current density of -25mA/cm2 for 60 min. The amount of biomimetically deposited Ca-P increased with the number of immersion steps. SEM images and XRD analysis of the Ca-P deposit indicated the initial formation of brushite with its monoclinic crystal structure and characteristic peak at 11.76 2?, and electrochemical conversion of brushite to hydroxyapatite on silk after electrochemical cathodization as confirmed by XRD and SEM analysis. Thus, a silk-fibroin-hydroxyapatite composite material prepared as a xenograft consisting of biocompatible components, and easily prepared as an economical bone segment replacement material with highly oriented fibers Daha fazlası Daha az

Kalender, Murat | Korkmaz, Emin Erkan

Other | 2017 | Turkish Journal of Electrical Engineering and Computer Sciences25 ( 3 ) , pp.2388 - 2398

Entity-linking systems link noun phrase mentions in a text to their corresponding knowledge base entities in order to enrich a text with metadata. Wikipedia is a popular and comprehensive knowledge base that is widely used in entity-linking systems. However, long-tail entities are not popular enough to have their own Wikipedia articles. Therefore, a knowledge base created by using Wikipedia entities would be limited to only popular entities. In order to overcome the knowledge base coverage limitation of Wikipedia-based entity-linking systems, this paper presents an entity-discovery system that can detect semantic types of entities t . . .hat are not defined in Wikipedia. The effectiveness of the proposed system was validated empirically through the use of generated data sets for the Turkish language. The experimental results show that, in terms of accuracy, our system performs competitively in comparison to the previous methods in the literature. Its high performance is achieved through a method that learns word embeddings for candidate entitie Daha fazlası Daha az