Elektronik ve Haberleşme Mühendisliği Bölümü

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    Citation Count: ŞİMŞEK, O. (2013). Design and implementation of a 1kw single phase grid tie inverter. Yayımlanmamış yüksek lisans tezi. Ankara: Çankaya Üniversitesi Fen Bilimleri Enstitüsü.
    Design and implementation of a 1kw single phase grid tie inverter
    (2013) Şimşek, Oğuz; Çankaya Üniversitesi, Fen Bilimleri Enstitüsü, Elektronik ve Haberleşme Mühendisliği Bölümü
    Renewable energy sources and their power processing equipments are gaining increasing importance in the market. Excess of energy harvested from a renewable source is either stored for future use or sold to other users that are in need of electrical energy at the time of harvesting. Since storage of excess energy is an ine fficient and costly process, a better way of dealing with excess energy is to transfer the energy to the interconnected power grid by means of appropriate power processing. In this thesis work, design and implementation of a high e - fficiency power processing equipment known as Grid Tie Inverter (GTI) to achieve energy transfer to the grid is studied. The target of this study is to convert low voltage direct current (DC) electrical energy harvested from the photo voltaic (PV) panels to high voltage alternating current (AC). The magnitude and phase of the processed alternating current is then controlled in a way such that the power ows towards the grid with a low DC and low reactive component. To achieve this goal, the voltage of the PV panels is stepped up to an appropriate DC link voltage by using a boost type converter known as the Z-Source. The required DC analysis and transfer functions iv of the Z-Source converter are obtained by the circuit averaging technique and a proportional-integral (PI) regulator is designed and implemented to stabilize the DC link voltage. The stabilized DC link voltage is then converted to alternating current using a full bridge inverter. The required grid voltage and phase information is obtained by digital implementation of a single phase time-delay based synchronous reference frame phase locked loop circuit (TDB-SRF PLL). The control of the current owing into the grid is carried out by using the D-Q synchronous reference frame approach. Hereby, the direct (D) and quadrature (Q) components of the grid current are calculated using Park's transformation. The magnitudes of the D and Q components are stabilized by separate digital PI controllers. The outputs of the PI controllers are then converted back to the rotating reference frame using the inverse Park's transformation. The output of the transformation is used as a control signal to drive the full bridge inverter. The scope of the thesis comprises both the modeling and simulation of the GTI components and the design and implementation of a prototype GTI. A thorough experimental evaluation con rms the practicability of the proposed design
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    Citation Count: DURMAZ, Ç. (2015). Development of a portable system for the detection of the microorganisms in meat product. Yayımlanmamış yüksek lisans tezi. Ankara: Çankaya Üniversitesi Fen Bilimleri Enstitüsü.
    Development of a portable system for the detection of the microorganisms in meat product
    (2015) Durmaz, Çağatay; Çankaya Üniversitesi, Fen Bilimleri Enstitüsü, Elektronik ve Haberleşme Mühendisliği Bölümü
    This thesis is related to a part of the Ministry of Science, Industry and Technology (MOSIT)'s Industry Thesis (SANTEZ) Program. The specific project number given by MOSIT to the project is 00973.STZ.2011-2. In the thesis, as a part of a Project group, I participated in all the activities of design and development of a new portable device that can detect and identify the food poisoning in a very short time, accurately, and reliably. The research Project Group consisted of the Project Coordinator Prof. Dr. Taner ALTUNOK, who was responsible for the management of the Project and technically all the aspects of the Project, Engin KIRAN, from IDC Company for electronic design and software, Onur ÖÇALAN and Melike AYTÜRK, from IDC company, for software development, and Gamze YAVAŞ and Cansu ÖZDEMİR, from IDC, are the biology experts. My main responsibility was to support the electronic and software design. I developed the image processor software used to identify the bacteria that cause the food poisoning in the images taken by a camera. The device, Biosensor System, was designed, developed and tested by the Project Group successfully. Thus, the SANTEZ Project was successfully completed and was tested and accepted by the MOSIT. The Biosensor System developed within the scope of the SANTEZ Project has extra capabilities to the devices available on the market. The image processing method we developed takes the image of a well where a chemical reaction had taken place by introducing an antigen into the food samples before. When the chemical reaction takes place between the food under test and the antigen in the well, some photons are emitted through the chemiluminescence mechanism. The irradiation intensities of the pixels in the image of the well were measured by an electron-multiplying charge-coupled device (EMCCD) camera. Our method defines the area of the wells identified by a mask, and then calculates the average intensity of all the intensity values belonging to pixels in the well image. A detection of the harmful microorganisms is made if the average intensity pertaining to the well exceeds a limit. A decision indicating a positive detection and identification of the harmful microorganism is made if this average intensity exceeds a threshold value determined
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    Citation Count: Albayaty, Abdullah Omran Ali (2017). Improvements in the finite element method and method of moments for the solution of electromagnetic problems / Elektromanyetik problemlerin çözümünde sonlu eleman metodu ve momentler metodunda gelişmeler. Yayımlanmamış yüksek lisans tezi. Ankara: Çankaya Üniversitesi Fen Bilimleri Enstitüsü.
    Improvements in the finite element method and method of moments for the solution of electromagnetic problems
    (Çankaya Üniversitesi, 2017) Albayaty, Abdullah Omran Ali; Çankaya Üniveristesi, Fen Bilimleri Enstitüsü, Elektronik ve Haberleşme Mühendisliği Anabilim Dalı
    In this thesis, two numerical techniques, the finite element method (FEM) and the method of moments (MoM) are improved for solving electromagnetic boundary value problems governed by differential and integral equations. The FEM is a numerical technique used to solve differential equations. The solution domain is divided into small intervals (elements), and the unknown function is calculated by finding an approximate solution by a truncated series of different shape functions. This approximate solution can be replaced with the original function in the differential equation. As a result, we get the matrix of equations that can be solved to obtain separate solution to the problem. In this thesis, we used the sigmoid function as a novel application, and compare the accuracy of FEM with the sigmoid function against the well-known linear and the step functions. Two examples of electromagnetic problems are presented. It is concluded that the sigmoid function under specific conditions yields the most accurate results. For MoM, this thesis presents a new mathematical algorithm for the solution of electromagnetic problems. This algorithm is schemed to be suitable for solving the singularity that exists in the solution matrix. This adaptive integration algorithm aims to avoid the singularity in the evaluation of the integral so called the Cauchy Principal Value integral. An example electrostatic problem is presented and it is proved that the novel method is accurate.
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    Citation Count: Bingöl, Hilal (2017). String stability analysis of Cooperative Adaptive Cruise Control (CACC) with actuator saturation / Aktüator Satürasyonu Altında Dizi Kararlı Kooperatif Otomatik Seyir Kontrolü. Yayımlanmamış yüksek lisans tezi. Ankara: Çankaya Üniversitesi Fen Bilimleri Enstitüsü.
    String stability analysis of Cooperative Adaptive Cruise Control (CACC) with actuator saturation
    (Çankaya Üniversitesi, 2017) Bingöl, Hilal; Çankaya Üniveristesi, Fen Bilimleri Enstitüsü, Elektronik ve Haberleşme Mühendisliği Anabilim Dalı
    Intelligent transportation systems aim at improving the efficiency and safety of transportation. In dense traffic, vehicles are aggregated to vehicle strings that travel on the same lane, whereby it is desired to maintain a small but safe distance between the vehicles. In the literature, this task is captured by the notion of string stability: fluctuations that are introduced by maneuvers of the leader vehicle should be attenuated by the follower vehicles. The literature provides various methods for achieving string stability under the assumption that the vehicles are modeled as linear systems. In this thesis, we study the case where vehicles are modeled as nonlinear systems and hence face actuation constraints as well as state constraints. Different methods are employed. First, a reachability analysis based on the level-set method determines the states that are reachable under limitations on the engine force of vehicles. It turns out in the thesis that, although the reachability analysis is the proper method to analytically address the problem of saturation, it is computationally not feasible due to the large state space of the vehicle model. As a remedy, a further analysis of the model is carried out for the special case of maneuvers. Based on the realistic assumption that the impulse response of the vehicle following model is positive, several sufficient conditions for the input signal of the leader vehicle are derived in order to preserve string stability under actuator saturation. The first set of condition is concerned with the computation of maximum/minimum input signal that generated based on optimal control solution. These maximum/minimum input signals depend on the initial velocity of the vehicle string. The second set of conditions allows computing suitable input signals of the leader vehicle analytically and is hence highly beneficial in practice. The obtained results are illustrated by extensive simulation experiments.
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    Citation Count: Çankaya, Erkam (2017). Trajectory generation for open/close gap maneuvers in vehicle strings / Araç dizilerinde boşluk açma/kapama manevraları için gezinge üretimi. Yayımlanmamış yüksek lisans tezi. Ankara: Çankaya Üniversitesi Fen Bilimleri Enstitüsü.
    Trajectory generation for open/close gap maneuvers in vehicle strings
    (Çankaya Üniversitesi, 2017) Çankaya, Erkam; Çankaya Üniveristesi, Fen Bilimleri Enstitüsü, Elektronik ve Haberleşme Mühendisliği Anabilim Dalı
    Cooperative adaptive cruise control (CACC) is an advanced technology allowing vehicle following at a small inter-vehicle spacing. In its classical usage, CACC assumes that vehicles are arranged in the form of a vehicle string and follow each other at a velocity-dependent distance. Nonetheless, practical driving situations include the case of lane changes, where vehicles can join or leave a vehicle string. In such case, it is required that gaps for joining vehicles are provided or gaps after leaving vehicles are closed in order to ensure safe and efficient driving. This thesis is concerned with gap opening and closing maneuvers in vehicle strings. Introducing a suitable control architecture, gap opening and closing maneuvers can be realized by the generation of feedforward input signals. To this end, the first contribution of the thesis is the development of five methods for the computation and representation of gap opening and closing trajectories that fulfill additional safety and comfort constraints. The first method is based on the solution of an optimal control problem, the second method uses a polynomial trajectory and plant inversion, the third method concatenates three polynomials and uses nonlinear programming to determine the polynomial coefficients, the fourth method uses a high-order polynomial and the fifth method uses concatenated polynomials in order to approximate the optimal control solution. A simulation study shows that the fifth method is particularly useful in practical applications since it computes trajectories that approximate the optimal control solution in real-time. The second contribution of the thesis is the implementation of a vehicle model that realizes CACC and additional feedforward signals in the form of a Matlab S-function.
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    Citation Count: KESKİN, A. (2013). Wireless optical wave propagation in underwater medium. Yayımlanmamış yüksek lisans tezi. Ankara: Çankaya Üniversitesi Fen Bilimleri Enstitüsü.
    Wireless optical wave propagation in underwater medium
    (2013) Keskin, Aysan; Çankaya Üniversitesi, Fen Bilimleri Enstitüsü, Elektronik ve Haberleşme Mühendisliği Bölümü
    In this thesis, the effects of the turbulence on the average transmittance are examined when the lowest order collimated Gaussian optical beam wave propagates in a wireless underwater medium. To observe the oceanic turbulence effect, the power spectrum of homogeneous and isotropic oceanic water combining the effects of salinity and temperature is used. Employing the Rytov method and the numeric integration, the effects of the parameters of power spectrum on the average transmittance are analyzed. Obtaining results with the help of Matlab program indicates that the rate of dissipation of the kinetic energy per unit mass of fluid is directly proportional to the average transmittance while the rate of dissipation of the mean-squared temperature is inversely proportional to the average transmittance. Increase in the link distance and decrease in the wavelength reduce the average transmittance. When the temperature-induced optical turbulence is dominant in the ratio of the salinity and temperature contributions to the refractive index spectrum, the average transmittance almost never decreases. However, the salinity-induced optical turbulence reduces the average transmittance sharply. Increasing the Kolmogorov microscale length, first the turbulence effect increases and the average transmittance decreases, but when the value of Kolmogorov microscale is further increased, the turbulence effect starts to decrease and the average transmittance increases, eventually a saturation is observed