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Enhanced Total Harmonic Distortion Optimization in Cascaded H-Bridge Multilevel Inverters Using the Dwarf Mongoose Optimization Algorithm
(Department of Agribusiness, Universitas Muhammadiyah Yogyakarta, 2024) Salih, Sinan Q.; Mejbel, Basim Ghalib; Ahmad, B.A.; Taha, Taha A.; Bektaş, Yasin; Aldabbagh, Mohammed M.; Hussain, Abadal-Salam T.; Hashim, Abdulghafor Mohammed; Veena, B.S.
Total harmonic distortion (THD) is one of the most essential parameters that define the operational efficiency and power quality in electrical systems applied to solutions like cascaded H-bridge multilevel inverters (CHB-MLI). The reduction of THD is crucial due to the fact that improving the system’s power quality and minimizing the losses are key for performance improvement. The purpose of this work is to introduce a new DMO-based approach to optimize the THD of the output voltage in a three-phase nine-level CHB-MLI. The proposed DMO algorithm was also subjected to intense comparison with two benchmark optimization techniques, namely Genetic Algorithm and Particle Swarm Optimization with regards to three parameters, namely convergence rate, stability, and optimization accuracy. A series of MATLAB simulations were run to afford the evaluation of each algorithm under a modulation index of between 0.1 and 1.0. The outcome of the experiment amply proves that in comparison with THD minimization for the given OP, the DMO algorithm was significantly superior to both RSA-based GA and PSO algorithms in their ability to yield higher accuracy while requiring lesser computational time. Consequently, this work could expand the application of the DMO algorithm as a reliable and effective means of enhancing THD in CHB-MLIs as well as advancing the overall quality of power systems in different electrical power networks.
The comparison study of PI and Sliding Mode control techniques for Buck-Boost converters
(Niğde Ömer Halisdemir Üniversitesi, 2024) Al-Attwani, Salah Hilo; Teke, Mustafa; Bektaş, Enes; Yaseen, Ethar Sulaiman Y.; Bektaş, Yasin; Civelek, Zafer
This paper compares the performance of a Sliding Mode Control (SMC) and Proportional-Integral (PI) controller under different voltage and load conditions. The study's findings underscore the need to account for load variations in system designs and to continuously seek system optimization irrespective of the controller type chosen. PI controller demonstrates effectiveness under certain circumstances. However, significant drops in voltage and current during abrupt load changes are obtained. On the other hand, SMC enables superior adaptability, efficiently managing voltage transients and load variations without any electrical disturbances, thereby maintaining system stability. A comparative analysis further emphasizes the SMC's superior time response and robustness against reference voltage changes. Consequently, SMC is proven to be a preferable choice over the PI controller in systems experiencing frequent voltage and load variations. However, both controllers achieve the potential for further response time optimization and stability.
Enhanced transformer protection using fuzzy-logic-integrated differential relays: a comparative study with rule-based methods
(Department of Agribusiness, Universitas Muhammadiyah Yogyakarta, 2024) Hussein, Raad Ibrahim Hussein; Gökşenli, Nurettin; Bektaş, Enes; Teke, Mustafa; Tümay, Mehmet; Yaseen, Ethar Sulaiman Yaseen; Bektaş, Yasin; Taha, Taha A.
The power transformers are the important part of electrical networks where transformer reliability and operational lifetime depends on sufficiently accurate and reliable protective means. Other traditional forms of differential protection that were developed initially also suffer from the inability to distinguish between a fault and normal operation such as inrush currents in transformers and CT saturation. This paper presents the development of an improved differential relay augmented by Fuzzy-Logic Control System (FLC), to improve (a) dependability, (b) performance of the existing transformer protection systems, and (c) accuracy in fault identification possible due to uncertainty and non-linearity in transformer operation. They include the proposed methodology compared to the traditional Rule-based current differential method in outlining the protection settings. MATLAB/Simulink model of the power transformer and protection methods suggested in the study form a part of the investigation. Computer simulations show that the presented scheme provides a substantial increase in the speed and resolution of fault detection and fault types identification relating to current differential method based on the Rule. The system’s accuracy rate is the average of 98% for internal faults and 95% for external faults while its response time is 25ms for internal faults and 30ms for external faults. Furthermore, the Fuzzy-Logic-based system has an 90% efficiency in detect the defect and 85% efficiency in identify the inrush currents. The findings of this research prove that the differential relay based on Fuzzy-Logic enhances the flexibility and reliability of transformer protection and opens the road to the introduction of further improvements in the intelligent protection systems in the future.
Effect of heat treatment on microstructure of near-eutectic Al-Ni-Mn alloy, and determination of mechanical and thermoelectrical properties
(Institute of Physics, 2024) Kaygısız, Yusuf
This study examined the impact of solution heat treatment on the microstructure, mechanical characteristics, thermophysical properties, and electrical resistivity of an Al-Ni-Mn near-eutectic alloy. The investigation focused on varying temperatures and holding periods. The composition of the Al-Ni-Mn near-eutectic alloy system was chosen as Al-5.3%Ni-1.0%Mn (wt). In the non-heat-treated sample, the matrix phase (?-Al) is in equilibrium with the intermetallic Al9(Mn,Ni)2 and Al3Ni phases. The hardness value of the non-heat-treated sample (49.8 kg mm?2) increased to 70.1 kg mm?2 with 2 h of solution heat treatment at 570 °C and then 8 h of artificial aging at 180 °C. The hardness value increased by approximately 41%. TE: 651.81 °C for the non-heat-treated sample and TE:648.79 °C for the heat-treated sample. Fusion enthalpy (?H) value was determined as 336.79 (J g?1) for the non-heat-treated sample and 516.36 (J g?1) for the heat-treated sample. Heat Capacity (Cpl) value was found to be 0.364 J g?1.K for the non-heat-treated sample and 0.560 J g?1.K for the heat-treated sample. The electrical resistivity value of the 2 h’ solution heat-treated sample at 600 °C reached its highest value.
Assessing microplastic pollution in a river basin: A multidisciplinary study on circularity, sustainability, and socio-economic impacts
(Academic Press Inc., 2024) Tavşanoğlu, Ülkü Nihan; Koraltan, İdris; Başaran Kankılıç, Gökben; Çırak, Tamer; Ertürk, Şeyma; Ürker, Okan; Güçlü, Pembe; Ünlü, Hülya; Çağan, Ali Serhan; Deniz Yağcıoğlu, Kıymet; Akyürek, Zuhal
Plastic pollution has emerged as a significant environmental challenge worldwide, posing serious threats to ecosystems and human health. This study seeks to explore the interplay among circularity, sustainability, and the release of microplastics within the freshwater ecosystems situated along the western Black Sea coast- Düzce, Türkiye. Employing a multidisciplinary approach that integrates environmental science, economics, and policy analysis, the research examines the current state of plastic pollution in the region, considering diverse land uses and socio-economic lifestyles. Conducted over four different seasons, the current study identifies the prevailing types of microplastics in the region. Fibers dominate, comprising 86.7% in each season, followed by film and fragments at 7.7% and 7.0%, respectively. Notably, polyethylene (PE) and polypropylene (PP) emerges as the primary polymer types. The distribution of polymer types varies across different land uses within the region, emphasizing the influential role of land use in shaping the abundance polymer composition. The comprehensive assessment of pollution, as reflected in the overall pollution load index (PLI) of the Melen River indicating a concerning level of pollution (PLI>1). Finally, the study unveiled the relationship between socio-economic activities as well as the seasonal precipitation patterns, and microplastic contamination in the region. This underscored the importance of site-specific mitigation measures on reducing the amount of microplastics. Lastly, incorporating sustainable practices within the circular economy framework fosters a harmonious balance between economic development and environmental protection in Türkiye.
Enhancing Multilevel Inverter Performance: A Novel Dung Beetle Optimizer-based Selective Harmonic Elimination Approach
(Department of Agribusiness, Universitas Muhammadiyah Yogyakarta, 2024) Taha, Taha A.; Neamah, Muthanna İbrahim; Ahmed, Saadaldeen Rashid; Taha, Faris Hassan; Bektaş, Yasin; Desa, Hazry; Yassin, Khalil Farhan; İbrahim, Marwa; Hashim, Abdulghafor Mohammed
This paper introduces a novel approach for enhancing the performance of multilevel inverters by applying a dung beetle optimizer (DBO)-based Selective Harmonic Elimination (SHE) technique. Focusing on a 3-phase multilevel inverter (MLI) with a non-H-bridge structure, the proposed method offers advantages such as cost-effective hardware implementation and eliminating the traditional H-bridge inverter requirement. To assess its efficacy, we compare the presented DBO-based SHE technique (DBOSHE) with Genetic Algorithm (GA) and Particle Swarm Optimization (PSO), evaluating their ability to determine optimal switching angles for achieving low-distorted load voltage. Unlike methods reliant on time-consuming calculations or fixed solutions, DBO provides a flexible approach, considering multiple possibilities to yield accurate switching angles. Using Simulink, harmonic component values and Total Harmonic Distortion (THD) are obtained for each optimization technique, specifically emphasizing on 9-level and 11-level MLI topologies. Our study aims to identify the most effective optimization technique for achieving lower THD and THDe values while eliminating odd-order harmonics from the 3-phase load voltage. Finally, we demonstrate the effectiveness of employing DBO for THD and THDe optimization within the SHE technique.
Dandelion Optimizer and Gold Rush Optimizer Algorithm-Based Optimization of Multilevel Inverters
(Springer Nature, 2024) Sağlam, Mustafa; Bektaş, Yasin; Karaman, Ömer Ali
With the increasing integration of renewable energy sources into distribution and transmission networks, the efficiency of cascade H-bridge multilevel inverters (MLIs) in power control applications has become increasingly significant for sustainable electricity generation. Traditionally, obtaining optimal switching angles of MLIs to minimize total harmonic distortion (THD) requires solving the selective harmonic elimination equations. To this end, this research aims to use two recently developed intelligent optimization algorithms, dandelion optimizer and gold rush optimizer, to solve this problem. To evaluate the effectiveness of the proposed algorithms, an eleven-level cascaded H-bridge MLI (CHB-MLI) was considered in the study. Simulation results for different modulation indices were obtained, and the accuracy and solution quality were compared with genetic algorithm and particle swarm optimization algorithms. MATLAB/Simulink-based models were used to verify numerical computations, ensuring the reliability of the findings. This research contributes to the field by providing insights into obtaining optimal switching angles and minimizing THD in MLIs by applying intelligent optimization algorithms.
Real-time control of Selective Harmonic Elimination in a Reduced Switch Multilevel Inverter with unequal DC sources
(Ain Shams University, 2024) Bektaş, Yasin
This study proposes a two-step method for generating switching angles in renewable energy systems that use multi-level inverters (MLIs) to reduce low-order harmonics. The Selective Harmonic Elimination Pulse Width Modulation (SHE-PWM) technique is used for MLI control, but it can be computationally intensive for real-time applications. To address this challenge, the proposed approach consists of a two-stage process. In the first stage, the SHE equations are solved offline using artificial ecosystem-based optimization (AEO). The obtained switching angles are then used to train an artificial neural network (ANN) prediction model in the second stage. The AEO-ANN-based SHE-PWM technique is applied to a reduced-switching, 3-phase, 7-level MLI. Simulations in MATLAB/SIMULINK show that the proposed method achieves accurate voltage control with less than 0.2% error, even for changing voltages, and reduces selected harmonics to less than 0.05%. The desired output voltage exhibits minimal total harmonic distortion (THD). This method offers a promising way to generate switching angles in renewable energy systems that use MLIs, improving power quality and reducing harmonic distortion.
Effect of heat treatment on corrosion resistance of al-ni-mn eutectic alloy in 3.5% nacl solution
(Konya Teknik Üniversitesi, 2024) Kaygısız, Yusuf
In this study, the effects of solution heat treatment (SHT) on how the Al-Ni-Mn eutectic alloy reacts to corrosion were looked into. The composition of the Al-Ni-Mn eutectic alloy was chosen as Al–5.3%Ni–1.3%Mn (wt). In solution heat treatment, firstly, the samples were kept at 570oC and 600oC for 2 hours and quenched with water at room temperature. Then, artificial aging was carried out by keeping 0-2-4 and 8 hours at 180oC. The corrosion behavior of the alloy was investigated by immersion tests in a 3.5% NaCl solution and electrochemical methods such as Tafel polarization curves and Electrochemical Impedance Spectroscopy (EIS). According to the immersion test results, the heat treatment applied at 600oC took the alloy to the more noble side and further increased its corrosion resistance. The ?-Al matrix phase in the Al-Ni-Mn alloy system preferentially dissolves in untreated and heat-treated samples, and SEM images reveal the presence of corrosion pits. The corrosion performance of the heat-treated sample at 570oC is the highest. Heat treatment reduced the corrosion current density, indicating a lower corrosion rate and higher corrosion resistance. Also, the open circuit potential of the Tafel polarization curves of heat-treated and unheat-treated samples at 570oC and 600oC was found to be -685 mV, -693 mV and -761 mV, respectively. Similarly, the corrosion resistance of heat-treated and untreated samples at 570oC and 600oC was found to be 58 k?, 433 k? and 408 k?, respectively.
Determination of microstructure and mechanical and thermophysical properties of Al-Si-Mg-XCr alloy
(Elsevier, 2024) Kaygısız, Yusuf; Palta, Çetin; Engin, Sevda
The study added different proportions of Cr to the Al-Si-Mg eutectic alloy and applied heat treatment to the quaternary alloy. So, the Al-Si-Mg eutectic alloy's microstructure and morphology were looked at after Cr was added and it was heated. In addition, the hardness, tensile strength, fracture surface analysis, and thermoelectric properties of newly produced Al-12.95 % Si-4.96 % Mg-X%Cr alloys were also determined. In the newly formed alloy, along with the expected Si and Mg2Si phases in the Al matrix phase, a randomly distributed CrSi2 binary intermetallic phase in a white hexagonal structure was observed with the effect of Cr addition. Additionally, a magnesium-rich Al9FeMg3Si5 intermetallic phase was observed, which we think was formed by the effect of Fe impurity atoms. Hardness and tensile strength values, which are the mechanical properties of the alloy, increased significantly after heat treatment. The hardness value of the 0.5 % Cr-added sample increased by approximately 77 % and reached 107.95 +/- 6.0 kg/mm2. At the same time, the hardness value of the intermetallic CrSi2 phase in the quaternary Al-12.95 wt%Si-4.96 wt%Mg-1.0%Cr alloy was found to be 794.3 +/- 30 kg/mm2. Similarly, the maximum tensile strength value of the 0.5 % Cr-added sample after heat treatment increased by approximately 105 % and reached 160.53 MPa. Melting temperatures (Tm) (K), fusion enthalpy (Delta H) (J/g), and specific heat Cpl (J/gK) were determined for non-heat-treated materials. The 0.5, 1.0, and 1.5 Cr-added samples had Tm of 563.38 degrees C, 558.44 degrees C and 572.61 degrees C, respectively. The Delta H value of samples with 0.5 %, 1.0 % and 1.5 % Cr addition is 605.70 (J/g), 579.92 (J/g) and 552.24 (J/g), respectively. Cpl was 0.724 J/g.K, 0.698 J/g.K and 0.653 J/g.K for 0.5 %, 1.0 %, and 1.5 % Cr-added samples. In both heat-treated and non-heat-treated samples, Cr enhanced electrical resistance.
The Effect of Mn Addition and Heat Treatment on the Microstructure, Mechanical, and Thermophysical Properties of Al-Si-Mg Eutectic Alloy
(Springer Science and Business Media Deutschland GmbH, 2024) Kaygısız, Yusuf; Palta, Çetin; Kaymaz, Tuba Çifçi; Engin, Sevda
The study added Mn at different rates to the Al–Si–Mg eutectic alloy and heat-treated the quaternary alloy. Therefore, the microstructure morphology of the Al–Si–Mg eutectic alloy was examined after Mn addition and heat treatment. Also determined were the hardness, tensile strength, fracture surface analysis, and thermoelectric characteristics of the newly produced Al–12.95%Si–4.96%Mg–X%Mn [X=0.5, 1.0, and 1.5 (wt.)] alloys. Along with the predicted Si and Mg2Si phases in the Al matrix phase, this investigation found a randomly distributed Mn-rich Al15Mn3Si2 intermetallic phase and a Mg-rich Al5Si3Mg2 phase. Mn-doped samples without heat treatment were somewhat softer than the parent alloy. After heat treatment, the hardness more than doubled for the Al–Si–Mg eutectic system and Mn-doped samples. After heat treatment, the alloy with 1.5% Mn added had the maximum hardness value of 94.3±5.0 HV. Heat treatment improved tensile strength by up to 80%, and the alloy with 0.5% Mn had 144.7 MPa. Melting temperatures (Tm) (K), fusion enthalpy (?H) (J/g), and specific heat Cpl (J/gK) were determined for non-heat-treated materials. The 0.5, 1.0, and 1.5 Mn-added samples had Tm of 566.30, 568.96, and 566.40 °C, respectively. The ?H value of samples with 0.5%, 1.0% and 1.5% Mn addition is 662.29, 657.93 and 639.11, respectively. Cpl was 0.788, 0.781, and 0.761 J/g.K. for 0.5%, 1.0%, and 1.5% Mn-added samples. In both heat-treated and non-heat-treated samples, Mn enhanced electrical resistance.
Makine Öğrenmesi ve Optimizasyon Yöntemleri ile Uzun Dönem Elektrik Enerjisi Tahmini: Türkiye Örneği
(Bandırma Onyedi Eylül Üniversitesi, 2023) Kahraman, Ömer Ali; Bektaş, Yasin
The rapid spread of industrialization has increased the need for energy today. However, optimization and machine learning algorithms have come to the fore in order to make predictable energy estimates in order to meet this emerging energy need. Particle swarm optimization (PSO), Lineer Regresyon (LR) and support vector regression (SVR) are included in these algorithms. In this study, using PSO, LR and GSR algorithms, Turkey's energy demand estimation between the years 2020-2040 was carried out. In order to make these estimations, the past population, exports, imports, gross domestic product (GDP) between 1980-2019 were used as input data, while energy consumption was used as output data. Regression square (R2) value, root mean square error (RMSE), mean square error (MSE), and mean absolute error (MAE) error metrics were used to evaluate the performance results of the PSO, LR, and GSR methods. Considering the R2, RMSE, MSE and MAE values, it has been determined that all methods have successful results. Anahtar Kelime: Particle Swarm Optimization Linear Regression Gaussian Process Regression Energy Demand Forecasting
Child tracking system using smartphone
(Institute of Advanced Engineering and Science, 2023) Taha, Taha A.; Hussain, Abadal-Salam T.; Desa, Hazry; Taha, Faris Hassan; Bektaş, Yasin
The number of missing children and kidnapping is on the rise in recent years. Every parent wills definitely going through an agonizing experience to have their children missing. Therefore, there are many safety measurements to prevent this incident from happening. The help of modern technologies is one of the ways to reduce children missing and kidnapping. A child can be tracked by using the global positioning system (GPS) and global system for mobile communication (GSM) technology. Advanced child monitoring systems are expensive. Not all families have the same living standards. For this purpose, a low-cost child tracking system is proposed in this study. The implementation of the proposed approach is reported in real-time.
Experimentally flight performances comparison of octocopter, decacopter and dodecacopter using universal UAV
(Elsevier B.V., 2023) Yıldırım, Şahin; Çabuk, Nihat; Bakırcıoğlu, Veli
This study presents a comparative analysis of different unmanned aerial vehicle (UAV) configurations using a proposed universal UAV. The octocopter, decacopter, and dodecacopter were experimentally evaluated through point tracking flight performances and vibration level analyses. To the best of our knowledge, this is the first study to conduct a comparative analysis of these configurations on the same platform. Our findings indicate that the dodecacopter exhibited the best overall performance, whereas the decacopter showed the lowest roll angle error. Notably, the implemented decacopter exhibited the highest pitch angle error and north position error due to its asymmetric rotor placement in the pitch axis. We observed that the octocopter demonstrated the best vibrationless flight performance, while increasing vibration magnitude was observed with an increase in the number of rotors.
Design and Experimental Validation of an Adaptive Landing Gear for Safe Landing on Uneven Grounds of VTOL UAVs in the Context of Lightweight and Fast Adaptations
(Institute for Ionics, 2023) Çabuk, Nihat
One of the most fundamental problems of rotary-wing aircraft that can take off and land vertically is that they cannot land safely when the ground on which they will land is too sloped. In case they have to make their landing, they inevitably face the risk of rolling over. The main source of this problem is that these vehicles have fixed landing gear. In this study, an important solution proposal is presented by performing an adaptive passive landing gear design and control for a four-rotor UAV with low takeoff weight, within the framework of the principle of fast adaptation to the ground, low cost, and weight. The experimental studies’ results indicated the usefulness of the proposed landing gear. This adaptive landing gear, produced within the scope of this study, has a total mass of 170 g, and it got the UAV to safely land on both sloped surfaces with 15 degrees and randomly uneven surfaces.
Red deer algorithm-based selective harmonic elimination technique for multilevel inverters
(Institute of Advanced Engineering and Science, 2023) Bektaş, Yasin; Karaca, Hulusi; Taha, Taha A.; Zaynal, Hussein I.
This paper proposed a red deer algorithm (RDA)-based selective harmonic elimination (SHE) method for multilevel inverters (MLIs). To eliminate the desired harmonic orders, the optimum switching angles of the MLI have been calculated using the proposed RDA. The calculated switching angles have been applied to the 3-phase cascaded H-bridged 11-level inverter. In addition, the performance of the proposed RDA method was compared with the results of methods such as the Newton-Raphson (NR) method, LSHADE/EpSin technique (LSHADE), whale optimization algorithm (WOA), and particle swarm optimization (PSO) used for the SHE problem in the literature. The results obtained prove that the proposed RDA optimization solves the SHE problems more effectively than other methods. It has also been observed that RDA produces good solutions in different modulation indexes.
Design and walking analysis of proposed four-legged glass cleaning robot
(Mersin Üniversitesi, 2023) Çabuk, Nihat
In this study, a legged and wheeled robot model was proposed for cleaning the glass of greenhouses. The robot has four wheels and four legs, each with three degrees of freedom (DOF). The design, kinematic analysis and simulation of the robot was carried out. Glass greenhouses are created by placing glass sheets on T-shaped iron bars arranged in parallel at certain intervals. The robot performs the glass cleaning task by performing two different movements on greenhouse roof. As a first movement, the robot moves like a train moving on the rail on iron bars with wheels, cleaning the glass as it travels. After cleaning the glasses placed between two iron bars along a column, as second movement, the robot passes the next column using legs. These two movements continue until the entire roof of the greenhouse is cleaned. Kinematic analysis of this robot, which is designed with mechanical properties that can make these movements, has been made. Walking simulation of the robot was carried out according to the kinematic analysis. The simulation results showed that this proposed robot can be used to clean glass on the greenhouse roof.
OPTIMAL PID CONTROLLER DESIGN FOR TRAJECTORY TRACKING OF A DODECAROTOR UAV BASED ON GREY WOLF OPTIMIZER
(Konya Teknik Üniversitesi, 2023) Yıldırım, Şahin; Çabuk, Nihat; Bakırcıoğlu, Veli
In this study, we aimed to find optimal PD controller gains to control orientation and position of a Dodecarotor UAV with minimum trajectory error. In this context, a cascaded PD controller approach which has velocity feedback in the inner loop and position feedback in the outer loop was adopted for each state (roll, pitch, yaw, altitude) in the flight control of the UAV. Subsequently, a fitness function was defined based on the system's time domain response and trajectory tracking error for each state, except the yaw angle, which is non-dominant in terms of trajectory tracking performance. Grey Wolf Optimizer (GWO) was used to obtain PD gains by minimizing the defined fitness function. At the same time, Particle Swarm Optimizer was used in order to benchmark the obtained results from GWO and to avoid a shallow solution space. The obtained PD controller parameters as a result of the optimization study of both algorithms were implemented to the system and the results were compared with each other. Finally, the gains that provided the best results for both algorithms were compared with each other and the results were discussed in terms of the time domain results and the actuator input smoothness. It has been observed that the GWO optimized controller provides a 40-46% improvement over PSO in all four different mass UAVs in terms of reducing axis position errors.
Red deer algorithm based selective harmonic elimination for renewable energy application with unequal DC sources
(Elsevier Ltd, 2022) Bektaş, Yasin; Karaca, Hulusi
This study aims to find the optimal switching angles in a cascaded H-bridge multilevel inverter (CHB-MLI) fed by photovoltaic (PV) panels, keeping the output voltage constant regardless of the panel voltage change and eliminating low-order harmonics. For this purpose, Red Deer Algorithm (RDA), a newly developed algorithm, has been applied to solve selective harmonic elimination (SHE) equations. Calculated switching angles are simulated by applying three-phase 7-level CHB-MLI in Matlab/Simulink environment. RDA optimization has been compared in performance to evolutionary algorithms such as particle swarm optimization (PSO), genetic algorithm (GA) and pigeon inspired optimization (PIO). The results show that in the case of unequal DC voltage, RDA can suppress selected harmonics accurately and quickly while controlling the fundamental voltage with a 0.02% error. The proposed RDA optimization can be used for multilevel inverters fed by any number of variable input voltages to eliminate selected harmonics and reduce total harmonic distortion (THD) without complex analytical calculations.
Tracking the microplastic accumulation from past to present in the freshwater ecosystems: A case study in Susurluk Basin, Turkey
(Elsevier, 2022) Feisal Almas, Fatma; Bezirci, Gizem; Çağan, Ali Serhan; Gökdağ, Kerem; Çırak, Tamer; Başaran Kankılıç, Gökben; Paçal, Elif; Tavşanoğlu, Ülkü Nihan
Microplastic pollution in aquatic ecosystems has become a global issue in recent years due to its presence everywhere around the world. Although several studies have explored the impact of the accumulation of those small particles in marine environments, comparisons of freshwater systems with marine environments are scarce. In the current study, due to the lack of long-term data on microplastic pollution, we used paleolimnological approaches to acquire the missing information regarding this hot topic. Two short cores were taken from Bursa province in Turkey, which is the center of industrial and agricultural production with many different sectors such as textile and manufacturing. The first core sample was taken from a relatively pristine environment, Lake Uluabat, and the second one was taken from a delta area where all the discharge coming from the basin flowed through to the Marmara Sea. The sediment core from the lake was dated back to the 1960's and the majority of the sample was dominated by fibers. Despite there being no uniform distribution pattern, the number of the microplastics showed decreasing trend after the lake became a Ramsar site. Due to the continuous mixing in the sampling area, there were obstacles via the dating of the Delta core. Nevertheless, the data showed that a high number and variety of microplastics have accumulated over the last decade in the province. This can be interpreted as microplastic pollution reaching the sea directly from the basin. These findings revealed that a plastic chronostratigraphy would give important temporal data regarding the microplastic accumulation in aquatic ecosystems.

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