Celik S.,Balikesir University |
Dinc D.,General Directorate of Highways |
Yaman R.,Balikesir University |
Ay I.,Balikesir University
Praktische Metallographie/Practical Metallography | Year: 2010
In welding technology, joining processes of different materials, which have dissimilar crystal structures are difficult. Welding of different materials becomes very important to reduce costs. Furthermore, the friction welding method is processed in lower temperature than the melting temperature. Especially, this is a big advantage to overcome difficulties that occur in the heat affected zone during usage of conventional methods. In this study, the weldability of AISI 304 stainless steel and AISI 1040 carbon steel by friction welding is studied. During the welding process, temperature variations in the welding zones were measured with an infrared temperature measurement device. After welding of the samples, tensile and hardness experiments were carried out. For metallographic investigations, optical microscope and scanning electron microscope (SEM) pictures were taken. Energy dispersive spectroscopy (EDS) analysis was carried out for composition investigations on welding and heat affected zones. As a result, these two steels could be joined by friction welding for industrial usage. © Carl Hanser Verlag,.
Kilinc S.,Izmir Tepecik Training and Research Hospital |
Tan S.,Izmir Tepecik Training and Research Hospital |
Kolatan E.H.,Dokuz Eylül University |
Ruscuklu D.,Biotechnology and Bioengineering Research and Application Center |
And 5 more authors.
International Urology and Nephrology | Year: 2014
Purpose: Warm-ischemia-induced injuries might be encountered during renal transplants from cadavers and healthy donors. Toll-like receptors (TLR) in ischemia-reperfusion (I/R) injury are one of the indicators of intracellular injury pathways. The intensity of ischemic injury is directly proportionate to high TLR levels. To minimize the I/R injury, we investigated TLR2 and TLR4 levels on rats, which were pretreated with tacrolimus (FK506) before I/R. Methods: Eight Wistar albino rats in the study group were administered .01 mg/kg intramuscular tacrolimus. Administration to the study group was performed 24 and 1 h before warm ischemia. Eight rats in the control group were injected with 0.1 c.c. of distilled water. Blood samples were collected from the tail veins of all the rats on the first, second and third days. Expression levels of TLR2 and TLR4 genes were analyzed using the polymerase chain reaction method, to determine any significant difference between the control and study groups on the days when blood was taken. Results: TLR2 (p = 0.045) and TLR4 (p = 0.022) levels in the study group were found to be statistically, and significantly, lower than those in the control group, on the second day following warm-ischemia- and reperfusion-induced injury. Conclusions: Administration of immunosuppressive drugs to healthy donor rats led to a statistically significant reduction in the expression levels of TLR2 and TLR4 in the early period. In light of the data obtained by this study, we hypothesize that a preoperative therapy on donors might have a role in preventing I/R injury. © 2013 Springer Science+Business Media.
A model suggestion for the determination of the traffic accident hotspots on the turkish highway road network: A pilot study [Sugestão de modelo para a determinação de pontos críticos de acidentes de tráfego na rede de estradas de rodagem da Turquia: Um estudo piloto]
Erdogan S.,Afyon Kocatepe University |
Ilci V.,Hitit University |
Soysal O.M.,Louisiana State University |
Korkmaz A.,General Directorate of Highways
Boletim de Ciencias Geodesicas | Year: 2015
Traffic accidents are very serious problems for human life and the environment. In road safety, it is crucial to identify the high risk locations to apply proper counter measures. This paper aims at introducing outcomes of a pilot project whose main goal is to develop a GIS based crash analysis system integrated with the quantitative methods for identification of high risk locations on road networks in Turkey. In this concept, traditional hotspot detection methods used in Turkey(crash frequency, rate, and severity) are compared with the spatial statistical methods including Moran‟s I, GetisOrd G and planar and network kernel density estimation in terms of their sensitivity to spatial characteristics of crash clusters. Many countries use traditional hotspot detection approaches such as crash frequency, crash rate, and crash severity as well as Turkey. In this project, we aimed at obtaining a model including different hotspot identification methods for the safety program of Turkey. In order to obtain the model, many hotspot detection methods will be used and compare stage by stage. In the first stage, the seven methods mentioned above are used and examined. Although some of these methods are compared in couple, there is no study using all these methods together extensively in the literature. Methods validated with a different spatial vantage points. Repetitiveness of hotspots in a seven years period are used to compare the methods. Meanwhile advantages and disadvantages of the methods according to location of hotspots are examined additionally. Results show that using planar KDE with Gi in the junction locations and using planar KDE with Moran‟s I in the straight road locations could improve the model while determining hotspots. © 2015 Universidade Federal do Parana. All rights reserved.
Calik U.,General Directorate of Highways |
Sadoglu E.,Karadeniz Technical University
Natural Hazards | Year: 2014
An experimental study was performed to investigate the effect of perlite and perlite-lime admixtures on classification, shear strength, and durability properties of an expansive soil containing smectite clay minerals. Two types of mixtures, namely soil-perlite and soil-perlite-lime, were prepared with different percentages of perlite and compacted with standard Proctor energy at their optimum water contents. Samples of 38 mm diameter and 76 mm height for durability tests and square samples of 60 mm edge for shear box test were taken and preserved until test time in a desiccator. Disturbed samples were also taken to determine liquid and plastic limits. The expansive soil shows behavior of fine sand and silt due to pozzolanic reactions in microstructure caused by addition of lime and perlite. Although apparent cohesion of treated soil decreased with increasing amount of perlite for both types of samples, perlite-lime-treated samples had higher apparent cohesion than only perlite-treated samples. Large increments in angle of shearing resistance were obtained with increasing usage of perlite. Samples stabilized with only perlite could not show enough durability at the durability tests based on volumetric stability and unconfined compression strength. However, samples stabilized with lime and more than 30 % perlite proved to have enough durability and shear strength. © 2013 Springer Science+Business Media Dordrecht.
Uysal U.,Sakarya University |
Sahin F.,General Directorate of Highways |
Chyu M.K.,University of Pittsburgh
Heat Transfer Research | Year: 2010
The heat transfer characteristics are analyzed in a rectangular cross section duct where impingement jet technique is applied for the purpose of heating and cooling. Heat transfer characteristics on surfaces are calculated using commercial CFD software, Fluent. Numerical results are compared with the experimental results obtained through a transient liquid crystal technique. To better present the heat transfer results, different cross-sectional size geometric models are used. The geometric models are of six in-line circular jets housed in a confined rectangular channel. As the jet temperature varies with time during a transient test, a time-depended solution method was selected in Fluent. One of the primary varying parameters in the present study is the magnitude of spacing between the jet exit and target plate. The jet Reynolds numbers range from 14,000 to 40,000 for every geometry. The effects of crossflow on the overall flow characteristics in the housed channel and heat transfer distributions on both target surface and jet-issuing plate are investigated. Comparison was made between the present numerical results and experimental data obtained earlier by the lead author, Uysal et al. . The companion experimental study was based on the transient thermochromic liquid crystal (TLC) measurements on detailed local heat transfer distributions on both the target surface and jet-issuing surface. © 2010 Begell House, Inc.
Gungor N.,General Directorate Of Highways
Multi-Span Large Bridges - Proceedings of the International Conference on Multi-Span Large Bridges, 2015 | Year: 2015
Gebze-Orhangazi-Izmir Motorway (Izmit Bay Crossing and Connection Roads) is one of the most important transportation infrastructure projects in Turkey. The South Approach Viaduct is located on an important part of Gebze-Orhangazi-Izmir Motorway Project and south of Izmit Bay Suspension Bridge. The project location crosses North Anatolian Fault and it lies on the secondary fault zone because of this, different approaches are implemented for the design and the construction of theViaduct. This paper outlines briefly the design criteria, the construction methodology and application stages of project; which is quite different from the traditional methods. © 2015, Taylor & Francis Group, London.