2019 Cilt 24 Sayı 1

Permanent URI for this collectionhttps://hdl.handle.net/11452/12532

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An artificial neural network (ANN) approach for solution of the transcendental equation of longitudinal vibration
(Bursa Uludağ Üniversitesi, 2019-02-20) Emül, Abdullah; Orhan, Sadettin; Aktaş, Gözde Rabia; Mühendislik Fakültesi; Makine Mühendisliği Bölümü
Study of mechanical vibration is one of the major issues in engineering applications. Especially, during the design and test stages of a mechanical component or system, vibration must be considered. When a vibration issue is studied theoretically, a differential equation called characteristics equation or equation of motion (EOM) is obtained. A solution of EOM gives vibrational behavior of an object considered. When vibration of a continuous system is studied, a transcendental equation is finally obtained, whose solution by classical methods is not possible. In this study, the solution of the transcendental equation which is derived from the longitudinal vibration of a bar with one end fixed and a mass at the other end was presented. For this purpose, an ANN model was constructed and the datasets were created for the ANN model. The effects of the number of neurons, input data, and training function on the model were examined. In addition, multiple regression models were developed using the ANN data also natural frequency formulation was obtained by ANN analysis for each mode. A finite element modal analysis was performed by ANSYS software. The results obtained by ANN and ANSYS were compared with analytic calculation and it was shown that they were in enough agreement.
Buck, boost and buck-boost converter designs with various metaheuristic methods
(Bursa Uludağ Üniversitesi, 2019-04-03) Vatansever, Fahri; Kuyu, Yiğit Çağatay; Mühendislik Fakültesi; Elektrik Elektronik Mühendisliği Bölümü
One of the basic circuit structures in the field of power electronics is DC-DC converters. As these design steps require many mathematical operations, these problems are hard to solve by hand. In addition, choosing the proper component values is always curial when adopting the computer-based designs to the real-world. In this study, the software is developed for the designs of buck, boost and buckboost DC-DC converters via metaheuristic algorithms that calculate the parameters of the circuits. The components of the specified DC-DC converters are selected via the software with a user-friendly interface, under the desired criteria from the industrial series (E12, E24 and E96), by using eight different metaheuristic algorithms (artificial bee colony, differential evolution, genetic algorithm, particle swarm optimization, cuckoo search, harmony search, lightning search and gray wolf optimizer). The designs and analyses of DC-DC converters that are chosen according to the type and features (determining/selecting the components in accordance with the specified industrial series) can perform easily, fast and effectively through the software developed for this purpose.
Comparison of the selected physical properties of elastane weft knitted fabrics before and after repeated launderings
(Bursa Uludağ Üniversitesi, 2019-01-24) Günaydın, Gizem Karakan; Çeven, Erhan Kenan; Eren, Hüseyin Aksel; Mühendislik Fakültesi; Tekstil Mühendisliği Bölümü
It was aimed to investigate the influence of washing cycle and fabric type on stretching (%), unrecovered elongation (%) and elastic recovery properties of plain knitted fabrics made of different ground yarn types having the same elastane ratio (%). For the plain knitted fabrics; Elastane ratio was kept constant as 5% for all fabric types whereas the ground yarns were selected as 70% polyester 30% cotton vortex yarn, 70% polyester 30%viscon ring yarn, 70% polyester 30%cotton ring yarn, 100%viscon vortex and 100% cotton ring spun yarns respectively. Knitted samples were objected to repeated laundering and flat dried after each washing cycle. Fabric weight (g/m2 ) after the washing cycles of 1, 5 and 10 were premeasured. Fryma fabric extensometer device was used for determining the stretching ratios (%), unrecovered elongation (%) and elastic recovery (%) of the samples both in wale and course way. Two-Way ANOVA was performed in order to investigate the influence of washing cycle and fabric type on stretching (%) and unrecovered elongation (%) properties of the elastane knitted fabrics.
Determination of buckling temperatures for elliptical FGM plates with variable thicknesses
(Bursa Uludağ Üniversitesi, 2019-02-07) Karapınar, Işıl Sanrı
In this paper, the thermal buckling loads of elliptical thin plates made of functionally graded material (FGM) with thicknesses that vary parabolically are examined. The aim is to study the effect of parabolic thickness variations in the directions of both axes on the thermal buckling of FGM plates. In the analyses, the boundaries are assumed to be simply supported and clamped. Rayleigh-Ritz method is applied to solve the partial differential equations. The Poisson’s ratios of the plates are kept constant, but their moduli of elasticity and thermal expansion coefficients are assumed to vary functionally in the thickness direction due to the material characteristics of FGMs. The study is carried out for several plate aspect ratios. Thermal buckling results of elliptical FGM plates with parabolically varying thicknesses are determined and the critical temperatures of those plates are obtained.
A novel multi-hop wireless network proposal to control elevator floor fixtures in low-rise and medium-rise buildings
(Bursa Uludağ Üniversitesi, 2019-04-05) Lajin, Muhammed Macit; Karlık, Sait Eser; Fen Bilimleri Enstitüsü; Elektronik Mühendisliği Ana Bilim Dalı
Wired communication systems used to control elevator floor fixtures have problems due to huge amount of cables used in implementation, long installation time, long troubleshooting time and chronic faults. This paper proposes a double-jump multi-hop wireless network for low-rise and mediumrise buildings to control elevator floor fixtures using wireless short packet protocol (WSP). Telegram success rate, telegram intensity, hop time and signal power measurements have been performed on the proposed network. Experimental results emphasize that telegram intensity of about 75 telegram/s guarantees 100 % telegram success rate. Average hop times of 16.1 ms and 17.5 ms for the first and second hops have been measured respectively and found to be enough for low-rise and medium-rise buildings. Signal power measurements show that proposed network may be capable of performing even triple jumps or more instead of double jumps contributing to the speed, telegram intensity and the performance of the network.

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