Communications, Series A2-A3: Physical Sciences and Engineering
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Item Estimating co2 Emissions By Using Energy Intensıty Data of Oecd Countries(Ankara Üniversitesi Fen Fakültesi, 2019-06-30) Gunduç, Semra; Eryiğit, Recep; Bilgisayar Mühendisliği; Mühendislik FakültesiIt is discussed that economic development has an essential effect on the country’s CO2 emission which plays an important role in global warming. In this research well-known machine learning algorithm Extreme Learning Machine, ELM, is used to investigate the relationship between CO2 emission and energy intensity for countries in OECD. The results indicate a strong correlation and the method perform well for estimation.Item Focusing, Imaging and Fourier Transforming With a Large Numerical Aperture, Dielectric Flat Photonic Crystal Lens in Metamaterial Regime(Ankara Üniversitesi Fen Fakültesi, 2019-06-30) Çolak, Evrim; Çakmak, Atilla Özgür; Elektrik-Elektronik Mühendisliği; Mühendislik FakültesiAn untraditional Gradient Index Photonic Crystal (GRIN PC) is employed within the long wavelength regime to exhibit focusing, imaging and Fourier Transforming. A very large numerical aperture is aimed by breaking the paraxial wave approximation and the slowly changing refractive index assumption. This untraditional GRIN PC is shown to exhibit very similar lensing characteristics as its analytically solvable counterparts demonstrate. The results suggest that Fourier Transforming together with Fractional Fourier Transforms can be obtained from the present design. The performance of the GRIN PC lens is very much dependent on the excitation source as it is expected from GRIN optics and adiffractional propagating beams over large distances can be obtained.Item Synaptıc Transmıssıon: A Model on the Formatıon Of End-Plate Potentıal and a Study on Sımulatıon(Ankara Üniversitesi Fen Fakültesi, 2019-06-30) Özbek, Levent; Temuçin, Çağrı; Cengiz, Bülent; Öztürk, Fikri; İstatistik; Fen FakültesiIn this study, the emergences of postsynaptic action potentials are investigated using simulation study which is depended on the statistical model of acetylcholine (Ach) quantal release theory at motor end-plate. It is supposed that the end-plate potentials (EPP) are sum of miniature end-plate potentials (MEPP) which are released as quantal and random in number (N). By the hypothesis that N number has a Poisson and MEPPs have a Gaussian distribution, EPPs are obtained by simulating distributions parameters. Our study suggests that the simulation of the EPPs are a convenient tool in understanding both physiological process of synaptic transmission and pathological process of neuromuscular junction.Item Investigating Doubly Charged Leptons at Future Energy Frontier Muon-Proton Colliders(Ankara Üniversitesi Fen Fakültesi, 2019-06-30) Ozansoy, Aysuhan; Fizik; Fen FakültesiWe study the doubly charged leptons considered in extended isospin models at muon-proton colliders. We respect the lepton flavor conservation and take into consideration the single production of the doubly charged leptons related to second generation. We give the effective lagrangian describing the doubly charged lepton gauge interactions. We calculate the signal and corresponding background cross sections and analyze the kinematical distributions to obtain the suitable cuts for the discovery. We choose the W-boson hadronic decay channel to get the accessible mass limits and couplings of doubly charged leptons for various muon-proton colliders.Item Efficient Chebyshev Economization for Elementary Functions(Ankara Üniversitesi Fen Fakültesi, 2019-06-30) Bekir, Esmat; Other; OtherThis paper presents economized power series for trigonometric and hyperbolic functions. It determines the smallest range over which a function need to be computed and scales the Chebyshev polynomials accordingly. Thus reduced degree polynomials (and hence reduced computations) can be obtained while maintaining the same accuracy as those unscaled higher degree polynomials.Item A Comparatıve Study: Voltage Multıplıers For RF Energy Harvestıng System(Ankara Üniversitesi Mühendislik Fakültesi, 2019-06-30) Sarı, Filiz; Uzun, Yunus; Other; OtherVoltage multipliers are widely used for energy harvesting processes to convert the received AC signal to DC signal, also enhanced the low level received signal. In this study, Villard, Dickson and Greinacher type voltage multipliers are analyzed without impedance matching and substrate materials to decide the effective voltage multiplier type depend on the inputs of the harvester. So, load resistance, input power and input frequencies’ effects are analyzed and compared with each other. Agilent Advanced Design System (ADS) is used for simulations. HSMS 2852 Schottky diode and capacitors are used for these voltage multipliers. Results show that, determining load resistance is important for evaluating high efficiency, e.g. efficiency differences are reached 33% between 2kΩ and 20 kΩ for Dickson voltage multiplier at 100 MHz input frequency. Furthermore, the best efficiency is obtained by Greinacher voltage multiplier for low input frequencies which is lower than 1 GHz but there are no significant differences are observed for high frequencies. This study shows that load resistance, input frequency and input power are important parameters for voltage multiplier selection and Greinacher voltage multiplier is the best choice to obtain high efficiency for low frequency application of RF harvesting.Item Quality of Software Projects – A Case Study(Ankara Üniversitesi Fen Fakültesi, 2019-06-30) Ayyıldız, Tülin Erçelebi; Kıral, Alper; Other; OtherIn software projects, many points that are overlooked such as time constraints and human factors are causing great problems in the future. By measuring the quality of software projects, problems that may arise in important parameters such as maintenance-repair, functionality and reliability can be eliminated. In this study, metrics that can be used for measuring maintainability quality attribute within the scope of ISO 9126 Quality Standard are examined. In order to perform the study, 40 open source object-oriented software was selected and code complexity analysis was performed. Values of metric sets such as Chidamber and Kemerer (CK), Lorenz and Kidd (LK) and McCabe's complex Suite were determined by the Understand Code Analysis tool. It was determined whether the obtained values exceeded the threshold values indicated in the literature. Frequencies of metrics passing threshold values were determined for 40 open source object-oriented software projects, and the consistency among the metrics was evaluated using WEKA Machine Learning Software and EXCEL Data Analysis Tool. When the results were evaluated, it was observed that in addition to CK metrics such as WMC, CBO, and RFC, which measure the maintainability quality attribute, NOC (CK), NIM (LK), and the ratio of comment/code metrics have been observed to yield significant measurement results.Item Desıgning a Secure Blockchain-Based Trading Platform for Internet of Things(Ankara Üniversitesi Fen Fakültesi, 2019-06-30) Osmanoğlu, Murat; Elbuz, Aydın; Tanrıöver, Ömer Özgür; Bilgisayar Mühendisliği; Mühendislik FakültesiBlockchain, a distributed database technology attracts intensive attention recently. It was first described in 1991 by Stuart Haber and W. Scott Stornetta, in order to prevent tampering for document timestamps. After that, Satoshi Nakamoto conceptualized this technology with his work, a peer-to-peer electronic cash system named as Bitcoin. Due to its authenticity, user anonymity and data immutability; this technology has also been applied to different areas ranging from finance, supply-chain managements to social services. In this paper, we propose a blockchain based application for trading data, collected from IoT devices. Our application enables the sellers to commercialize their data in exchange of the currency produced by the application. The application also utilizes smart contracts to establish trust between both sides of the exchange. Furthermore, we discuss the security and reliability of the system componentsItem Prıvacy-Preservıng K-Nearest Neıghbour Interpolatıon Method ın an Outsourced Envıronment(Ankara Üniversitesi Mühendislik Fakültesi, 2019-06-30) KALIDEEN, Muhammad Rifthy; Osmanoğlu, Murat; Tuğrul, Bülent; Bilgisayar Mühendisliği; Mühendislik FakültesiOne of the most emerging computer technologies of this decade is cloud computing that allows data owners to outsource their storage and computing requirements. It enables data owners to avoid the costs of building and maintaining a private storage infrastructure. While outsourcing data to cloud promises significant benefits, it possesses substantial security and privacy concerns, especially when data stored in the cloud is sensitive and confidential, like a business plan. Encrypting the data before outsourcing can ensure privacy. However, it will be very difficult to process the cipher text created by the traditional encryption method. Considering this fact, we propose an efficient protocol that allows a query owner to retrieve the interpolation of the top k records from two different databases that are closest to a query point. Note that the databases are stored in two different cloud service providers in encrypted form. We also show that the proposed protocol ensures the privacy and the security of the data and the query point.Item Operation Tests of the 260 mhz 1500 w Solid State RF Amplifier at Tarla Facility(Ankara Üniversitesi Fen Fakültesi, 2019-12-01) Karslı, Özlem; Çalok, Evrim; Elektrik-Elektronik Mühendisliği; Mühendislik FakültesiTurkish Accelerator and Radiation Laboratory (TARLA) will be the first accelerator-based user facility in Turkey. The facility is under construction at the Institute of Accelerator Technologies of Ankara University. Based on the state-of-art superconducting technology, TARLA accelerator offers a multi-experimental facility providing a variety of accelerator-based radiation sources for users coming from various fields like chemistry, physics, biology, material sciences, medicine and nanotechnology. TARLA consists of two acceleration lines: the first one is the injector that provides high current continuous wave (CW) electron beam at 250 keV energy, and the second one is the main accelerator that comprises of two superconducting (SC) cryomodules separated by a bunch compressor in order to accelerate the electron beam up to 40 MeV energy. Two normal conducting accelerators, so called subharmonic (SHB) and fundamental (FB) buncher cavities whose operation frequencies are 260 and 1300 MHz, respectively, are used to compress the electron bunches from ~600 ps to ~10 ps. SHB cavity is powered by a 1500 W Radio-frequency (RF) power amplifier. Currently, the electron gun training, and superconducting modules acceptance tests, personal safety system, and helium cryogenic system commissioning tests are performed simultaneously. In this study, we present the operation tests of the 1500 W RF amplifier in the scope of the commissioning tests of injector line which showed phase drift coefficents of ~0.5 deg/Co and ~0.67 deg/Co in repeated tests. Moreover, the importance of constancy of the water pressure in the water-cooling line for phase constancy of the delivered power has become evident as a result of current obervations.Item Preprocessing Steps in Fmri: Smoothing(Ankara Üniversitesi Fen Fakültesi, 2019-12-01) Daşgın, Hacer; Yaman, Ali; Akdi, Yılmaz; Fizik; Fen FakültesiFunctional magnetic resonance imaging is a technique with a primary and dominant effect in the investigation of the cognitive functions of the brain since it has a complex structure. In this study, data obtained from single subject was examined. First statistical parametric mapping results were obtained after applying the standard preprocessing steps with including smoothness. Spatial smoothing was performed using a 3 mm Gaussian kernel which is twice of the voxel size. Second, statistical parametric mapping results were obtained with applying standard preprocessing steps without smoothing. The effects of these two applications on the mapping results were compared for selected slices and locations in terms of statistical and pattern.Item A Comparison of deep Learning Based Architecture With a Conventional Approach for Face Recognition Problem(Ankara Üniversitesi Fen Fakültesi, 2019-12-01) Ünal, Fatime Zehra; Bilgisayar Mühendisliği; Fen Bilimleri EnstitüsüThis paper addresses a new approach for face recognition problem based on deep learning strategy. In order to verify the performance of the proposed approach, it is compared with a conventional face recognition method by using various comprehensive datasets. The conventional approach employs Histogram of Gradient (HOG) algorithm to extract features and utilizes a multi-class Support Vector Machine (SVM) classifier to train and learn the classification. On the other hand, the proposed deep learning based approaches employ a Convolutional Neural Network (CNN) based architecture and also offer both a SVM and Softmax classifiers respectively for the classification phase. Results reveal that the proposed deep learning architecture using Softmax classifier outperform conventional method by a substantial margin. As well as, the deep learning architecture using Softmax classifier also outperform SVM in almost all cases.Item Magnetocaloric Effect Around Curie Temperature in Ni50-x CuxMn38Sn12B3 Shape Memory Ribbons(Ankara Üniversitesi Fen Fakültesi, 2019-12-01) Kızılarslan, Olcay; Other; OtherThe magnetocaloric effect in Ni50-xCuxMn38Sn12B3 ribbons depending on the Cu substitution (x= 0, 1, 3) was investigated around the Curie temperature. The purpose of the present study was to analyze the magnetocaloric effect around a second order phase transition (around the Curie temperature) which has a smaller thermal hysteresis compared to a first order phase transition (Martensitic transition). The Curie temperature of the ribbons shifted to higher temperatures with increasing Cu content. A conventional magnetocaloric effect (MCE) was observed around the Curie temperature when the ribbons are subjected to a magnetic field change of 5 T. The magnetic entropy changes were calculated based on the isothermal magnetization data using thermodynamic Maxwell equation. The highest magnetic entropy change and the refrigerant capacity was obtained for the x=1 ribbon.Item Robust Refractive Index Fiber Sensor Based on Two Up-Tapers Placed in Down-Taper(Ankara Üniversitesi Fen Fakültesi, 2019-12-01) Navruz, İsa; Bilsel, Mustafa; Elektrik-Elektronik Mühendisliği; Mühendislik FakültesiIn this study, a novel tapered optical fiber sensor based on a Mach–Zehnder interferometer (MZI) for refractive index measurement is proposed. Our sensor is constructed with two up-tapers symmetrically placed in a down-taper single mode fiber. Although its waist diameter is as thick as 55 μm, the sensor can measure the refractive index. Simulation results demonstrate RI sensitivities of -94 nm/RIU and -125 nm/RIU at the lower and higher wavelength of the spectrum. The sensor is extremely robust, it can be easily manufactured and it can be used not only for RI but also for simultaneous strain and temperature measurements.Item Band Reduction for Target Detection in Hyperspectral Images(Ankara Üniversitesi Fen Fakültesi, 2020-06-30) Şimşek, Murat; Ilgın, Hakkı Alparslan; Elektrik-Elektronik Mühendisliği; Mühendislik FakültesiDue to the high spectral resolution, hyperspectral images need large data storage and processing time. Indeed, its high dimensional structure requires high computational complexity, especially for target detection. In order to overcome these problems, band reduction methods have been proposed. In this paper, we compare PCA and SNR-based band reduction methods to improve target detection performance in hyperspectral images. Experimental results show that band reduction methods not only reduce processing time, but also increase accuracy rate.Item Evaluatıon Of Ms-Dıal And Mzmıne2 Softwares For Clınıcal Lıpıdomıcs Analysıs(Ankara Üniversitesi Fen Fakültesi, 2020-06-30) Koçak, Engin; Other; OtherLipidomics covers analysis of all lipid species in an organism. Lipid metabolism is one of the key factors to understand cellular processes at molecular level. Lipidomics has been used to find diagnostic and prognostic biomarkers in clinical sample (plasma, serum, urine, tissue). Today mass spectroscopy based approach dominates lipidomics and several computational platforms have been developed to process raw mass spectra data. However, there is no routine procedure for data processing in lipidomics. In present work, two different bioinformatics platforms, which are MS-DIAL and MZmine2, was compared for lipidomics analysis of plasma sample. Peak detection, identification and quantification parameters were investigated to understand advantages and disadvantages. In peak detection process, it was observed that MZmine2 detected more peak than MS-DIAL at same threshold level. In identification process, Lipidmaps database was used for identification. MZmine2 identifies more lipid than MS-DIAL. Semi-quantification is very important to find differentially expressed lipid species and biomarkers in clinical studies. MS-DIAL and MZmine2 calculated normalized peak intensities and results were compared to understand reproducibility. Average relative standard deviation of all peaks was calculated and results showed that MS-DIAL gives more reproducible results than MZmine2. In conclusion, MZmine2 and MS-DIAL could be used in clinical lipidomics studies.Item RF Antenna Desıgn For Button-Type Beam Posıtıon Monıtors Usıng Bıo-Inspıred Optımızatıon Methods(Ankara Üniversitesi Fen Fakültesi, 2020-06-30) Aydın, Ayhan; Bostancı, Gazi Erhan; Bilgisayar Mühendisliği; Mühendislik FakültesiAccelerator based facilities are in a leading position for crafting many scientific and technical innovations for a wide range of application from aviation to medicine. Beam Position Monitors (BPMs) are critical diagnostics tools for such facilities. This study presents bio-inspired methods known as Particle Swarm Optimization and Evolutionary Algorithms in order to design RF antennas for button-type BPMs. Our results show that the antenna parameters obtained using this multiple objective approaches present suitable SNR and linearity values for signal processing. It is found that using an antenna radius of 5.5 mm and beam-pipe radius of 17.5 mm, we can obtain SNR values around 40 dB which can be electronically processed.Item A Study On The Search Potentıal of Doubly Charged Leptons At The Sppc Based Ep Colliders(Ankara Üniversitesi Fen Fakültesi, 2020-06-30) Ozansoy, Aysuhan; Albayrak, Oğuzhan; Fizik; Fen FakültesiWe consider the single production of doubly charged leptons which take part in the extended weak isospin models and have exotic electric charges such as at the SppC based electron-proton (ep) colliders. We introduce the effective lagrangians describing the doubly charged lepton gauge interactions with SM leptons. We calculate the decay widths and production cross sections as a function of doubly charged lepton mass. We deal with the process and plot the kinematical distributions for the final state electron both for the signal and corresponding background. We perform a cut-based analysis to obtain the mass limits and couplings of doubly charged leptons at the SppC based ep colliders with the center-of-mass energies of TeV and TeV.Item An Artifact Reduction Method for Block-Based Video Coding(Ankara Üniversitesi Fen Fakültesi, 2020-06-30) Ilgın, Hakki Alparslan; Akbulut, Ahmet; Elektrik-Elektronik Mühendisliği; Fen FakültesiMost of the image/video coding standards are based on discrete cosine transform which is a block-based coding scheme with a disadvantage of blocking effects at low bit rates. In this paper, we propose a hybrid method which consists of downsampling/upsampling, significance map coding and local cosine transform to reduce the disadvantage of lossy compression and is also compatible with current standards. Experimental results show that performance of the proposed method is better than the conventional approaches.Item Study Of Transportatıon Problem Of Iron And Steel Industry In Turkey Based On Lınear Programmıng, Vam And Modı Methods(Ankara Üniversitesi Fen Fakültesi, 2020-06-30) Askerbeyli, Rehile; Other; OtherThe subject of this study is the investigation of the minimization of the total transportation costs for finished product produced by Alter Iron and Steel Industry Company in its own production facilities in Karabuk. Firstly, the current situation in the Iron and Steel Industry in the world and Turkey are briefly discussed. In the second stage, the distribution to the demand point from the factory operating in the Iron and Steel Sector is considered as the basic problem. The demand points were determined as geographical regions. We have two targets: the total cost to be minimized and the total amount of goods to be sent from supply center to the demand centers to be equal to the total demand or supply amount. The optimum solution of the transportation model were solved both the traditional transportation model methods such as Vogels Approximation Method (VAM), Modified Distribution (MODI) method and the linear programming method. The optimal solution for last model was found using the R /SIMPLEX package program. Obtained results by different approachs are discussed. Critical aspect of this problem is to use the single source transportation model, where all demand amounts are met from a single production center.