2018 Cilt 23 Sayı 3

Permanent URI for this collectionhttps://hdl.handle.net/11452/12497

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Analysis of surface plasmon resonance sensing based on phase-detection in the infrared range
(Bursa Uludağ Üniversitesi, 2018-10-17) Koç, Aykut
Using phase detection in Surface Plasmon Resonance (SPR) sensing has potential improvements to the conventional intensity detection based SPR. Other than the phase detection and intensity detection based SPR in the visible range of the spectrum, employing SPR sensing principles in the infrared range by the use of silicon has also some promising advantages. Combining these two, in this paper, phase detection-based SPR sensing in the infrared range is studied using a mathematical model and numerical simulations. The results are compared with the results obtained by the simulations in the visible range. Performance improvements are noted by the use phase detection in the infrared range.
The chaos-based approaches for actual metaheuristic algorithms
(Bursa Uludağ Üniversitesi, 2018-10-17) Kuyu, Yiğit Çağatay; Vatansever, Fahri; Mühendislik Fakültesi; Elektrik Elektronik Mühendisliği Bölümü
Along with rapid developments in computational technologies, evolutionary/heuristic/metaheuristic algorithms have frequently used in many applications to solve optimization problems. Nowadays, new algorithms are being developed and improvements are being made to existing algorithms. In this study, chaos-based modifications have been proposed for recently developed metaheuristic algorithms: Backtracking Search (BS), Grey Wolf Optimizer (GWO) and Vortex Search (VS), and the algorithms have been analyzed by detailed comparisons. The proposed approaches are based on generating new values through chaos maps, rather than some random numbers normally used in the algorithms, to improve their solutions. In addition, some modifications are performed to the structural operations of the algorithms used in the optimization process by taking advantage of chaosbased values. The performances of the algorithms are evaluated by considering two metrics: convergence rates and statistical results. Experiments demonstrated that the performance of the algorithms with the proposed modifications based on the chaos approach, are better than, or at least comparable to, the original algorithms.
Coastal pollution ın Istanbul
(Uludağ Üniversitesi, 2018-09-28) Kopuz, Esin Bozkurt; Erim, Aycan; Altındağ, Saffet
Quantities of pouches filled with marine debris and packaging (kg) collected during coast and beach cleaning, the amount of waste (m3 ) collected during sea surface cleaning and moss work (kg), and the amount of sludge removed during stream rehabilitation (m3 ) were analyzed in Istanbul, Turkey between 2013 and 2016. Seasonal changes have been identified in these quantities. The quantity of packaging pouches collected during coastal cleaning had increased over time, reached its highest level in 2016. High values were observed in September due to heavy rainfall and in the summer due to waste transported from picnic areas. However, low values were seen for all parameters in winter. This increase in waste quantities can be eliminated by taking various precautions such as recycling or reusing plastic bags and bottles instead of throwing waste away. For a cleaner sea and coast, public education can be developed to encourage these precautions. In addition, economic measures can be taken such as selling plastic shopping bags instead of giving them free of charge.
A comparative study for hyperspectral data classification with deep learning and dimensionality reduction techniques
(Bursa Uludağ Üniversitesi, 2018-10-16) Ortaç, Gizem; Özcan, Gıyasettin; Mühendislik Fakültesi; Bilgisayar Mühendisliği Bölümü
In recent years, hyperspectral imaging has been a popular subject in the remote sensing community by providing a rich amount of information for each pixel about fields. In general, dimensionality reduction techniques are utilized before classification in statistical pattern-classification to handle high-dimensional and highly correlated feature spaces. However, traditional classifiers and dimensionality reduction methods are difficult tasks in the spectral domain and cannot extract discriminative features. Recently, deep convolutional neural networks are proposed to classify hyperspectral images directly in the spectral domain. In this paper, we present comparative study among traditional data reduction techniques and convolutional neural network. The obtained results on hyperspectral image data sets show that our proposed CNN architecture improves the accuracy rates for classification performance, when compared to traditional methods by increasing the classification accuracy rate by 3% and 6%.
Development of a Phase-OTDR interrogator based on coherent detection scheme
(Bursa Uludağ Üniversitesi, 2018-12-14) Yüksel, Kıvılcım; Jason, Johan; Wuilpart, Marc
We present in this work, the experimental demonstration of a phase-sensitive Optical TimeDomain Reflectometer (phase-OTDR) having coherent detection scheme. An analysis algorithm has also been developed to calculate amplitude and phase evolution of the experimental phase-OTDR traces. The efficiency of the analysis algorithm to determine the position of the applied vibration has been verified for a single and two simultaneous vibrations. The slow-time analysis results show a good agreement with the mathematical calculations discussed in the paper. This work could have a technological implication in many fields such as distributed vibration sensor for railway monitoring applications.
Effect of dental implant dimensions on fatigue behaviour: A numerical approach
(Bursa Uludağ Üniversitesi, 2018-11-30) Topkaya, Hüsna; Kaman, Mete Onur
In this study, the effect of the implant shape on fatigue behavior was investigated with the finite element method. The implant material used was Ti6Al4V. The examination focus on the effect on the implant life with respect to changes in the crest and root dimension, thread depth, thread pitch, implant length, implant diameter, chamfer length, chamfer radius, and groove length to implant length ratio. Models were subjected to fatigue analysis according to ISO 14801 standard with ANSYS finite element software. The mean stress correction theory is chosen in fatigue life solutions. As a result, the parameters seen to have the most effect on dental implant fatigue behavior were the implant length and diameter. The parameters with the most effect on the implant screw fatigue were pitch and the height of the tooth.
Effect of wet laundering on stretching and air permeability properties of polyester warp knitted fabrics with different fabric weights
(Bursa Uludağ Üniversitesi, 2018-10-08) Günaydın, Gizem Karakan; Çeven, Erhan Kenan; Mühendislik Fakültesi; Tekstil Mühendisliği Bölümü
Warp knitting technology combines the two properties of dimensional stability and elasticity which are provided from woven and knitted fabrics separately. These fabrics consist of several threads (warp) which are formed as loops via needles and run through the fabric mainly in a vertical direction. These fabrics may be produced on a flat or a circular warp knitting machines. This study aims to investigate the influence of washing cycles (1, 5 and 20) on stretching (%) and air permeability properties of the polyester warp knitted fabrics of different weight. In order to analyze the effect of washing process on stretching ratios (%) and air permeability of the samples; Fyrma fabric extensometer and SDL Atlas M021A model Air Permeability Tester devices were used respectively. Additionally, the changes in fabric weight according to washing cycles of 1, 5 and 20 were also evaluated. According to test results; the stretching properties and air permeability values of the polyester warp knitted fabrics produced in different weights varied according to the laundering cycle which emphasized that caring processes should also be considered during the evaluation of mechanical properties (such as stretching, air permeability properties) of polyester warp knitted fabrics.
Intuitionistic fuzzy number based group decision making approach for personnel selection
(Uludağ Üniversitesi, 2018-09-12) Efe, Burak; Efe, Ömer Faruk
The most appropriate personnel selection is a very important issue for an organization’s success due to the increasing competition in global market. Traditionally, Saaty’s consistency method is used to check the consistency of the experts’ judgments in personnel selection problem and the inconsistency judgments can be sent to return to the experts for reevaluation, which is time consuming and sometimes undesired by experts, or can be extracted from decision making process. A perfect multiplicative consistent intuitionistic preference relation (IPR) will be repaired the inconsistent IPRs of the experts into a consistent one automatically. There is no paper about personnel selection using integrated intuitionistic fuzzy analytic hierarchy process method (IFAHP)-IFVIKOR (intuitionistic fuzzy VlseKriterijumska Optimizacija I Kompromisno Resenje) approach under group decision making with perfect multiplicative consistent IPR. This paper presents an integrated multi-criteria decision making method for personnel selection with perfect multiplicative consistent IPR under intuitionistic fuzzy environment. Priority value of criteria has been defined by utilizing IFAHP method and the most appropriate personnel among candidates has been found by utilizing intuitionistic fuzzy VIKOR. The application of personnel selection is conducted to illustrate the effectiveness of the proposed method in a logistic firm. The personel selection is realized according to a questionnaire responded by three experts in human resources management area. Five criteria for personel selection are defined through literature review and the judgments of expert team. K1 (self-confidence) is defined as the most important criteria for personnel selection of the specified logistic firm by using IFAHP. Alt3 is defined as the most suitable personnel for the specified logistic firm by using IFVIKOR.
Investigation of the effect of apparel fabrics structure on air permeability and thermal comfort properties
(Bursa Uludağ Üniversitesi, 2018-11-08) Gürarda, Ayça; Zengin, Tuğba; Tosun, Gökçe; Mühendislik Fakültesi; Tekstil Mühendisliği Bölümü
Fabric structure has a major effect on air permeability and thermal comfort properties of apparel fabrics. Air permeability and thermal comfort properties of apparel depend on fabric structural properties such as weave type, fabric thickness, weight, yarn density and cover factor. Thermal conductivity, thermal diffusivity, thermal absorptivity, thermal resistance and air permeability should be measured to test thermal comfort properties of fabrics.The purpose of this study is to investigate the effect of the apparel fabrics structure on air permeability and thermal comfort properties. For this reason, air permeability and thermal comfort properties of viscose / polyester blended woven fabrics of different structures which are widely used in apparel have been examined. According to the results, a negative correlation was observed between weight, thickness, cover factor and air permeability of the fabrics. A positive correlation was observed between weight, thickness, cover factor and thermal conductivity of the fabric samples. A positive correlation was observed between weight, cover factor and thermal absorptivity of the fabric samples. Also positive correlations were observed between thickness- thermal resistance and thickness- thermal diffusivity of the fabric samples.
Kinetics of the esterification of propionic acid with isobutyl alcohol over Amberlyst 36 and Amberlyst 70
(Bursa Uludağ Üniversitesi, 2018-11-23) Çıtak, Alime; Hoşgün, Halit Levent
The esterification of propionic acid with isobutyl alcohol has been studied in a batch reactor in the presence of Amberlyst 36 and Amberlyst 70 catalysts. Reaction parameters applied in this study are speed of agitation (500-1000 rpm), particle size of catalyst (400-600 µm, 600+ µm), temperature (318- 348 K) and catalyst loading (4-12 g-dry resin/L). A pseudo-homogeneous kinetic model was derived and all thermodynamic and kinetic parameters were calculated. Forward reaction rate constant for Amberlyst 36 and Amberlyst 70 determined as follows: (k1=160171 exp (-56689/RT) (L mol-1 min-1) (k1=293314 exp (-557292/RT) (L mol-1 min-1). In a comparison of the two catalysts used in this study, experimental results showed that Amberlyst 70 is more effective than Amberlyst 36.
Making an X-ray undulator ready for commissioning: Procedures subsequent to fabrication until tunnel installation
(Bursa Uludağ Üniversitesi, 2018-12-17) Ketenoğlu, Bora
In this study, sequence of events for an X-ray undulator generating Free Electron Laser (FEL) pulses down to hard X-rays of the electromagnetic spectrum, are discussed in detail. As soon as an undulator arrives to a Magnetic Measurements Hutch (MMH), a series of treatment steps start to make it ready for commissioning, beginning with a high-precision magnetic alignment procedure. Once Hall probe and undulator are accurately aligned to each other, then gap-dependent measurements begin to create tuning lists. After completion of mechanical tuning of poles, MMH 3D-coordinates have to be transformed to the coordinates of tunnel, where many undulator cells will be sequenced one after another along a linear path. Here, all optical, mechanical and magnetic procedures that an X-ray undulator experiences before commissioning, are thoroughly explained. Furthermore, effects of different types of Hall probes on magnetic measurements, are discussed as well. Finally, whole algorithm subsequent to fabrication until tunnel installation (i.e. optical and magnetic alignment, pole tuning, phase jitter therapy etc.), are summarized by means of the results of magnetic measurements taken in three identical MMHs of European XFEL facility.
A new automata based approximate string matching approach and web interface for bioinformatics algorithms
(Bursa Uludağ Üniversitesi, 2018-10-16) Koca, Burak; Özcan, Gıyasettin; Mühendislik Fakültesi; Bilgisayar Mühendisliği Bölümü
In this study, we present a new web interface for major bioinformatics algorithms and introduce a novel approximate string matching algorithm. Our web interface executes major algorithms on the field for the use of computational biologists, students or any other interested researchers. In the web interface, algorithms come under three sections: Sequence alignment, pattern matching and motif finding. In each section, we introduce algorithms in order to find best fitting one for specific dataset and problem. The interface introduces execution time, memory usage and context specific results of algorithms such as alignment score. The interface utilizes emerging open source languages and tools. In order to develop light and user-friendly interface, all parts of the interface coded with Python language. On the other hand, Django is used for web interface. Second contribution of the study is novel A-BOM algorithm, which is designed for approximate pattern matching problem. The algorithm is approximate matching variation of Backward Oracle Matching. We compare our algorithm with popular approximate string matching algorithms. Results denote that A-BOM introduces %30 to %80 short runtime improvement when compared to current approximate pattern matching algorithms on long patterns.
Novel, practical and reliable analytical models to estimate electrical efficiency of buildingintegrated photovoltaic/thermal (BIPVT) collectors and systems
(Bursa Uludağ Üniversitesi, 2018-11-08) Cüce, Pınar Mert
Building-integrated photovoltaic/thermal (BIPVT) collectors are multifunctional products that replace conventional building materials in parts of the building envelopes, such as the facades and roofs. BIPVT collectors serve as novel building envelope material that can generate thermal and electrical energy simultaneously to be utilised in buildings. Despite the remarkable potential of BIPVT collectors and systems in mitigating energy consumed in building sector, until recently, they have received only limited attention since there has been no comprehensive attempt to date to optimise BIPVT collectors in terms of design, operation and climate oriented performance parameters. Electrical efficiency is a key performance parameter for BIPVT collectors. In this respect, easy, fast and reliable determination of electrical efficiency of BIPVT collectors is of vital importance for preliminary performance assessment of this technology under various design, operational and environmental conditions. Therefore in this research, novel, practical and reliable analytical expressions are developed to estimate electrical efficiency of air type BIPVT collectors as a function of design and climatic parameters. The most common configuration of BIPVT collectors (glass to glass BIPVT collector) is considered within the scope of this study, and analytical expressions are developed for this design. The accuracy of the analytical expressions is verified through previous experimental works in literature conducted under different climatic conditions. The results indicate that the electrical efficiency of glass to glass BIPVT collector is in good accordance with previous literature.
Optimal design of automotive suspension springs using differential evolution algorithma
(Bursa Uludağ Üniversitesi, 2018-11-08) Yıldız, Betül Sultan
The automotive industry has been growing steadily and paying attention to develop technologies and production processes in the world. Automotive companies are facing great competition due to the increasing number of companies and the rapid increase in customer expectations as a result of developing technological products. In order to compete, automotive manufacturers need to meet the expectations of customers and governments, such as vehicle weight, collision safety, fuel emissions and vehicle comfort. In order to ensure that competition is sustainable, companies should design lighter and more efficient parts that require less processing costs with more precise operations. Recently, concerns about fuel consumption and air pollution have been reported. Meta-heuristic optimization methods have been widely used for optimization of vehicle component over the past three decades. In this paper, differential evolution (DE) algorithm is used for optimization of the coil spring design, which is one of the suspension spring types. Using the DE algorithm, the mass of the coil spring decreased by about 29.3 %. The results show that the DE algorithm provides better solutions as previous methods in the literature.
Simulation of phase equilibria in high chromium white cast irons
(Bursa Uludağ Üniversitesi, 2018-11-08) Akyıldız, Öncü; Candemir, Duygu; Yıldırım, Hakan
In this study, using the Materials Calculator software program, the pseudo binary phase diagrams (i.e. isoplethal maps) of high chromium white cast irons (~19% in weight) with different molybdenum contents were simulated. In order to test the accuracy of the calculated phase diagrams, the transformation temperatures read from the diagrams at certain compositions were compared with the phase transformation temperatures measured using Differential Scanning Calorimetry (DSC) analysis of the samples produced by casting in the same composition followed by slow cooling. With the same purpose, low temperature phases read from the phase diagrams were compared with the crystalline phases determined by X-Ray Diffraction (XRD) of the casted samples. Simulated diagrams predicted an increase in the amount of secondary M23C6 carbides with increasing molybdenum content. The validity of this prediction was tested by determining the phase distribution and phase compositions in the casted samples by means of metallographic examinations and Scanning Electron Microscopy (SEM) - Energy Dispersive Spectroscopy (EDS) analyzes. When the hardness values of the samples were taken into consideration, it was seen that the hardness increased from 44.90 to 51.05 HRC with a 1% increase in Mo content and a corresponding increase in the amount of secondary carbides without any heat treatments. Results show that theoretical predictions and experimental measurements are in accord and estimating phase equilibria in multi-component systems is of practical importance.

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