2019 Cilt 24 Sayı 3

Permanent URI for this collectionhttps://hdl.handle.net/11452/12619

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    Evaluation of reinforcing bars ratio effects on scc beam-column joint performance
    (Bursa Uludağ Üniversitesi, 2019-09-21) Ghatte, Hamid Farrokh
    Beam-column joints require a high ductility during the unexpected loadings that necessitate the need for ductile concrete in such unprotected locations. Alternatively, self-compacting concrete (SCC) is a sort of concrete which has generated tremendous interest throughout the last decades in order to reach a ductile structural elements during the seismic actions. Specific properties of this type of concrete include high performance, high resistance against segregation and needless to internal or external vibration in order to compact. In the seismic regions, ductility is one of the most important factors in the design of reinforced concrete (RC) members, especially structural joints flexural performance; it is due to the enhance in the capability of plastic deformability. This paper describes load-displacement behavior of experimental and theoretical analysis of four SCC beam-column joints with different percentage of the ratio of the reinforcing bars (ρ). In the theoretical phase of this investigation three-dimensional nonlinear finite element method (FEM) model i.e., Seismostruct was used and the load-deflection diagrams were plotted to compare the test results with the numerical output. The experimental results and nonlinear FEM modeling indicate that using SCC as a workable concrete in beam-column joints of reinforced concrete structures has satisfactory performance in terms of ductility and energy dissipations.
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    Evaluation of the RadFET radiation sensor performance in 18 MV-external beam
    (Bursa Uludağ Üniversitesi, 2019-11-18) Yeğen, Dinçer; Yılmaz, Ercan; Morkoç, Berk; Kahraman, Ayşegül; Fen Edebiyat Fakültesi; Fizik Bölümü; 0000-0002-9573-5805; 0000-0002-1836-7033
    The radiation response of RadFET irradiated with 18 MV X-rays emitted from a linear accelerator was examined on threshold voltage shifts and trap densities. The measured threshold voltages were compared before and after irradiation. Trap densities calculated using various techniques in the gate oxide and oxide/silicon interface were interpreted. The ΔVth – D graph showed excellent linearity of up to just about 2 Gy. The RadFETs response to radiation started to deviate from linearity after 2 Gy due to increasing oxide trapped charges induced by electric field screening. The experimental outcomes are in good accordance with the fitting function given for RadFETs. Fixed and switching traps formed by irradiation were investigated. The density of the fixed traps was significantly higher than the density of the switching traps. From the threshold voltages measured under zero gate voltage in a certain time interval, the percentage fading range was calculated as 0.004-1.235%.
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    Finite element stress and modal analysis of bimetal spur gears
    (Bursa Uludağ Üniversitesi, 2019-11-18) Yılmaz, Tufan Gürkan; Karpat, Fatih; Mühendislik Fakültesi; Makine Mühendisliği Bölümü; 0000-0003-3772-7871; 0000-0001-8474-7328
    Involute spur gears subject to damage on their fillet and contact areas because of local stresses. There is no significant stress except these regions. Based on this fact, different materials could be used for high stress and low stress regions provided that suitable fusion method is available. This kind of design change results in weight reduction, and it ensures to reduce CO2 emissions for vehicles. In this study, natural frequencies and root stress of bimetal spur gears were analyzed. Results were compared with full steel spur gear. The steel was used for high stress region. Aluminum and magnesium alloys were used as low stress zone.
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    Fotovoltaik sistemlerin projelendirme, kurulum ve işletilmesinde önemli faktörler
    (Bursa Uludağ Üniversitesi, 2019-09-27) Yiğit, Abdulvahap; Arslanoğlu, Nurullah; Eker, Buket Seçil; Fen Bilimleri Enstitüsü; Makine Mühendisliği Bölümü; 0000-0002-9183-0098; 0000-0003-4970-4490; 0000-0002-7582-2004
    Güneş enerjisi bakımından zengin olan ülkemizde Güneş Enerjisi Santralleri (GES) ile ilgili önemli yatırımların yapıldığı bilinmektedir. Ancak bu yatırımların fizibilitelerinin çok doğru yapıldığını söylemek oldukça zordur. GES santrallerinin projelendirilmesi, kurulması ve işletilmesi aşamalarında birçok yanlışların yapıldığı ve bunun sonucu santrallerin verimsiz çalıştığı görülmektedir. Bu santrallerin projelendirilmesinde dikkat edilmesi gereken önemli noktalar olduğu gibi, kurulum ve işletmesinde de dikkat edilmesi gereken hususlar bulunmaktadır. Projelendirme esnasında yer seçimi, panel doğrultusu, panel açısı ve gölgeleme önemli parametreler arasındadır. GES santrallerinde panel sıcaklığının, rüzgarın ve kirliliğin panel verimini önemli ölçüde etkilediği bilinmektedir. Bu çalışmada; GES santrallerinin panel açısı, panel yönü, gölgeleme, sıcaklık, nem, rüzgar, kirlilik gibi parametrelerin panel verimine etkileri literatürde verilen çalışmalarla ortaya konulup, konunun tartışması yapılmıştır. Ayrıca, güneş takip sistemlerinin fotovoltaik sistemlerin verimleri üzerine etkileri tartışılmıştır. GES santrallerinin projelendirilmesi, kurulumu ve işletilmesi ile ilgili öneriler sunulmuştur.
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    The harmonic elimination in inverters with metaheuristic approaches
    (Bursa Uludağ Üniversitesi, 2019-11-21) Vatansever, Fahri; Kuyu, Yiğit Çağatay; Mühendislik Fakültesi; Elektrik Elektronik Mühendisliği Bölümü; 0000-0002-3885-8622; 0000-0002-7054-3102
    Inverters which convert DC voltage into AC voltage are widely used in the field of power electronics. During the conversion from DC voltage to AC voltage, some of the harmonics can occur. Harmonics which are one of the most important parameters in the field of energy/power systems determine the power quality. Therefore, one of the crucial steps is the elimination/suppression of harmonics in the outputs of the inverters. It is required to solve complex equations with multiple variables in this elimination process. In this study, a software is developed and eight different metaheuristic algorithms/approaches (backtracking search, cuckoo search, electromagnetic field optimization, harmony search, Harris hawks optimization, interior search, vortex search, Yin-Yang-pair optimization) are used for the elimination of the chosen harmonics by determining suitable switching angles. The desired harmonics are eliminated in the chosen inverter circuits via the software with a user-friendly interface easily, fast and effectively, and the results can be observed both numerically and graphically through the this software.
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    A novel method for performance improvement of slow start congestion control method in packet switched networks
    (Bursa Uludağ Üniversitesi, 2019-12-19) Preveze, Barbaros
    By the introduction of all IP networks with the smart homes, smart phones, car multimedia systems wearable technologies and IP TV’s, the number of internet related devices and the number of applications have increased. This has generated an increased quantity of bandwidth usage in packet switching networks. Therefore, the betterment of the bandwidth usage and the system performance has become more significant. Thus, there is a large number of works in the literature attempting to improve the network performance. For this purpose, generally the modifications of used methods in the network structures are preferred, rather than making major hardware based modifications requiring more financial support. In this work, a novel method called Return Back to threshold (RBT) is proposed to be applied to packet switched networks for a better congestion control.
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    Numerical analysis of the alveolar spaces and human tissues for nanoscale body-centric wireless networks
    (Bursa Uludağ Üniversitesi, 2019-10-25) Akkaş, Mustafa Alper
    This paper investigates the propagation of Terahertz (THz) electromagnetic waves inside the human body and discusses a model of the system performance of Nanoscale Body-Centric Wireless Networks inside the alveolar spaces and human tissues. THz band wireless communication enables new applications especially in nanoscale wireless communication. The model developed in this paper calculates the total absorption loss, path loss and capacity properties of EM waves propagating through the Alveolar Spaces and Human Tissues in nanoscale environment for THz band wireless communication. Based on the modeling of noise level and path losses, the channel capacity is calculated. The results show that Wireless Nanosensor Networks (WNSNs) can communicate through the human body. According to the numerical analysis of the model several transmission windows which are ω1 = [0.01 THz – 0.5 THz], ω2 = [0.58 THz – 0.74 THz] and ω3 = [0.77 THz – 0.96 THz] have been found for Nanoscale Body-Centric Wireless Networks. The longest and lowest transmission window which is in the range of 0.01 THz – 0.5 THz values have been analyzed for blood, plasma, RCBs and water to design universal nanonode for Nanoscale Body-Centric Wireless Networks at gases in lungs and blood.
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    Synchrotron radiation: From storage ring to a hard X-ray beamline
    (Bursa Uludağ Üniversitesi, 2019-04-29) Ketenoglu, Didem
    In the present study, a general overview covering the consecutive steps, starting with the release of electrons from an electron source until the generation of synchrotron radiation, is presented. A brief introduction regarding the main characteristics and fundamental components of third generation light sources as well as the radiation characteristics of different Insertion Devices are discussed. Following a concise description of a typical hard X-ray synchrotron beamline, synchrotron radiation based X-ray Raman scattering spectroscopy, which is a non-resonant inelastic hard X-ray technique, is explained. Finally, liquid water oxygen K-edge absorption spectrum recorded with a resolution of 0.8 eV at 10 keV utilizing X-ray Raman spectrometer at PETRA III facility of DESY is presented and compared to the spectrum from the literature measured by conventional X-ray absorption spectroscopy