Browsing by Author "Almali, M. Nuri"

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A Comparison of Hot Deck Imputation and Substitution Methods in the Estimation of Missing Data
(Gazi Univ, 2011) Yesilova, Abdullah; Kaya, Yilmaz; Almali, M. Nuri
It is of great importance to obtain data in an accurate and incomplete way for adequate conclusions to be drawn from investigations conducted. Due to various reasons, certain parts of an investigation might not be observed, and as a result of this, data might be missing and obtained incompletely. Missing value may not only be based on a single variable but also a multitude of variables. In this study, missing data in different proportions and belonging to more than a variable were produced. When data were considered within a context which is missing completely at random, Hot Deck imputation, random Hot Deck imputation and substitution methods (mean, median) were compared in the estimation of missing value. As a result of analysis, Hot Deck imputation method was found to be more effective in the estimation of missing value.
Comparison of the Output Parameters of the Memristor-Based Op-Amp Model and the Traditional Op-Amp Model
(Springer, 2022) Parlar, Ishak; Almali, M. Nuri
A new operational amplifier (op-amp) model has been proposed using a memristor emulator based on the linear TiO2 drift model. Simulation studies and numerical analyses of the new op-amp model designed using memristor are given. Frequency, unit, switching and electrical characteristic tests of the proposed op-amp model were performed. The parameter comparisons of the traditional op-amp and the proposed op-amp model are given in a detail table. In addition, the efficiency of the proposed op-amp model was realized with application circuits, and the reliability of the system was verified with the results.
Control of 2-Dof Trms Mimo System Using Fopid & Fostsmc Method
(Gazi Univ, Fac Engineering Architecture, 2023) Abukan, Yusuf; Almali, M. Nuri
The control design of a helicopter twin rotor multiple-input and multiple-output (TRMS) nonlinear System with two degree freedom is a very complex work. The TRMS system consists of the main and tail rotors connected by a beam. In order to balance the TRMS system, both rotors angles are made by changing the speeds of the DC motors to which the rotors are connected.In order to ensure that the TRMS system works in balance, Proportional-integral-derivative (PID), Fractional order PID (FOPID), Sliding mode (SMC), Super twisting sliding mode (STSMC) and Fractional order super twisting sliding mode (FOSTSMC) control methods was used. Simulation studies were carried out in the MATLAB/Simulink program to determine the control parameters. Experimental studies were carried out using the most successful methods found in simulation studies. In both simulation and experimental studies, the main propeller FOPID and tail propeller FOSTSMC method gave the best results compared to other control methods.
Design of a 21-Level Multilevel Inverter With Minimum Number of Devices Count
(Wiley, 2023) Karakilic, Murat; Hatas, Hasan; Almali, M. Nuri
Multilevel inverters (MLIs) have attracted the attention of researchers for their needs in industrial applications, renewable energy systems, and electric vehicles. MLIs require a large number of power electronic components to synthesize higher levels at the output voltage. However, overuse of power electronic devices increases the complexity, losses, and cost of MLIs. In this study, a new MLI has been proposed with a reduced number of power switches. The basic unit of the proposed MLI comprises only three independent DC sources and 10 switches (eight unidirectional and two bidirectional) to produce 21 levels at the output voltage waveform. The nearest level control (NLC) modulation method has been used to produce gate pulses. Furthermore, three extension topologies have been proposed to generate a higher number of levels, and the extension parameters have been compared with recently introduced and conventional topologies. The comparative study shows that the proposed MLI topology requires fewer components in terms of power electronics parameters than the others. On the other hand, the presented first extension study that can be used for all non-extendable basic units is one of the prominent values of the study. Simulation studies showing modulation methods, switching patterns, and signal outputs were performed with Matlab/Simulink. A prototype of the proposed main module has been realized and tested in the laboratory with an FPGA processing board. Experimental results have been verified with simulation results, and the performance of the proposed topology has been proven.
Design of Hybrid Switched Diode Multilevel Inverter Using Single Dc Source
(Springer Singapore Pte Ltd, 2024) Karakilic, Murat; Almali, M. Nuri
This paper presents a novel design of a 21-level switched diode multilevel inverter using a High-Frequency Link (HFL) and a single DC source. The inverter structure consists of 10 power switches and 2 diodes, which significantly reduces the number of components compared to existing topologies. Despite the utilization of HFL for generating multiple voltages, the analysis reveals that the majority (65%) of the power is directly drawn from the single DC source, while only a small portion (35%) passes through the HFL. This reduces the size of the high-frequency transformer and the need for a large DC-DC converter. The proposed topology achieves 21 levels with a low output total harmonic distortion (THD) of 3.99% without the use of additional filters. These features make it suitable for various applications, including electric vehicles and motor systems.
Experimental and Simulation Results of Wien Bridge Oscillator Circuit Realized With Op-Amp Designed Using a Memristor
(Springer, 2022) Parlar, Ishak; Almali, M. Nuri
In this study, a new op-amp model was created by re-designing the internal structure of the traditional operational amplifier (741 family) circuit element with a linear dopant drift TiO2 memristor (LDDTM) emulator model. The optimized working conditions and states of this proposed op-amp model were determined. Wien bridge oscillator circuit realized with memristive based op-amp model has been investigated on oscillating start time, settling time, fast fourier transform (FFT) analysis and output parameters. In addition, the efficiency of the wien bridge oscillator circuit realized with a memristor-based opamp has been tested with application circuits and the accuracy and applicability of the proposed memristor-based opamp model has been extensively examined theoretically and supported by experimental and simulation results. Finally, both the simulation and experimental results of the oscillator circuits realized with a memristor-based opamp are presented in detail in tables.
Locational Classification of Walnut (Juglans Regia L.) Genotypes Collected From Lake Van Basin by Using Mixture Modeling
(Academic Journals, 2010) Yesilova, Abdullah; Ozrenk, Koray; Kaki, Baris; Almali, M. Nuri; Balta, Fikri
In mixture modeling, it is assumed that the data set shows a heterogeneous structure. This heterogeneity is defined as unobservable heterogeneity. The data set's heterogeneity produces serious deviations in the parameter estimates and the standard deviations. Heterogeneity is overcome when the data set divides itself into homogeneous sub-populations. Thus, while homogeneity is attained for sub-populations, the heterogeneity between the sub-populations is tried to be put forward. Akaike's information criteria (AIC), Bayesian information criteria (BIC), and Entropy classification criteria are used to determine the number of sub-populations. After the number of sub-populations is determined, the model determines the probability that each observation will fall within a particular sub-population. In this study, the classification of districts based on fruit traits is achieved by applying mixture modeling to walnut fruits collected from eight districts. According to the AIC, BIC, and entropy criteria, a model with five sub-populations was chosen where the data set is the most distributed. Therefore, it was determined that each district does not form a different population according to the studied walnut fruit traits, but are distributed into five sub-populations. The fourth sub-population had the most desirable traits for walnut improvement, and the highest proportion of these traits came from the naturally grown populations of Adilcevaz and Ahlat districts.
Research on Effects of Environmental Factors on Photovoltaic Panels and Modeling With Matlab/Simulink
(Wydawnictwo Sigma-n O T Sp Z O O, 2012) Rustemli, Sabir; Dincer, Furkan; Almali, M. Nuri
In the early days of photovoltaic panels, some 50 years ago, the energy required to generate a photovoltaic panel was more than the energy the panel could generate during its lifetime. As a result of many years of research and experimental studies with today this time can drop up to 3-4 years according to the incentive policies of the some countries. Only obstacle to widespread adoption of photovoltaic panels is cost of their. Therefore, even small studies on photovoltaic panel have great importance to reduce the cost of photovoltaic panel. One of the most important ones is the panel temperature and environmental effects because these factors are affected the panel temperature. In this study, environmental factors that affect to electricity generation capacity of photovoltaic panels have obtained as detailed style with modeling and simulation is designed by Matlab/Simulink programme. Also, environmental factors is added to the model and is entered the system. In addition to this situation were applied on loaded. With this modeling the effects of environmental factors for photovoltaic panels are designed and discussed as detailed by Matlab/Simulink programme.
Single-Stage Modified Vienna Rectifier Sepic Ac-Dc Led Driver
(Elsevier, 2025) Gurcam, Kenan; Almali, M. Nuri
This paper presents an innovative approach by combining a modified first-stage Vienna rectifier with a single- stage SEPIC converter. The proposed Vienna rectifier structure significantly reduced the switch stress. This allows the use of switches with low voltage values and reduced resistances. The use of a non-electrolytic capacitor in the output stage contributed to extending the life of the LED driver. These features enhance the efficiency of the proposed driver. The recommended LED driver complies with the mandatory standards specified in IEC61000-3-2 for Class C loads. To verify the effectiveness of this proposed system, a setup of an 18 W LED driver operating was presented and simulated. This research aims to address power factor, switch stress, and harmonic distortion issues commonly associated with LED driver circuits, contributing to more efficient and compatible LED lighting systems.