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Gazi University Journal of Science
Number of Followers: 0  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2147-1762
Published by Gazi √úniversitesi Homepage  [9 journals]
  • Early Estimation of Sewerage Line Costs with Regression Analysis

    • Authors: Murat SUERİ; Mürsel ERDAL
      Abstract: In Turkey, an average of 450 sewer line tenders are made annually and the total line length of these works is approximately 11000000 m. It is very important for both the investor and the contractor to know the costs of the sewer networks with such a large business volume. In this study, models are developed for early estimation of sewage line costs by the regression analysis method. Data belonging to 182 sewer line projects were used in the development of the models. Data on pipe diameter, line length, excavation depth, manhole amount, excavation amount, filling amount, filling type, shoring type, excavation class and real cost parameters were determined through the projects. Correlations between the determined parameters were specified and the parameters suitable for regression analysis were selected. As a result; among the developed estimation models, the equation using all selected parameters with a correlation coefficient of R² = 0.911 gave the most successful result.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • Effect of Ta Content on Microstructure and Phase Transformation
           Temperatures of Ti75.5-Nb25.5 (%at.) Alloy

    • Authors: Safar MOHAMMED; Fethi DAĞDELEN, Ibrahim Nazem QADER
      Abstract: β-titanium shape memory alloys are used as shape memory-based biomedical applications and superelastic materials because they are made up of non-toxic components. Also, their behaviors are more semilar with that of human bone and dental biological tissues, such as biocompatibility, superior corrosion resistance, low density, and low modulus of elasticity. In the current study, the effect of Ta additive on the physical properties of Ti-Nb alloy has been investigated. Ti-Nb-Ta alloy samples were produced such that the Tantalum (Ta) element was substituted instead of Niobium (Nb), and the induction arc melting was used to melting the mixed powders. To investigate the crystal structure, microstructure, and phase transformation temperatures of all samples, the X-Ray Diffraction (XRD), Scanning Electron Microscopic (SEM), and Diffraction Scanning Calorimetry (DSC) measurements have been used. Both β-rich and α peaks were observed in the XRD and SEM measurements. Also, the DSC results revealed that the Ti-Nb-Ta alloys have only austenite transformation temperatures and their phase austenite phase transformation were decreased by the effect of Ta additive, additionally, the enthalpy change in〖 E〗_3 sample ( Ti_75.5 Nb_22.5 Ta_2 (%at)) has the highest value, while E_4 sample ( Ti_75.5 Nb_21.5 Ta_3 (%at)) has the lowest respective value. 
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • Current and Future Trend Opportunities of Thermoelectric Generator
           Applications in Waste Heat Recovery

    • Authors: Mohammad Ruhul Amin BHUİYAN; Hayati MAMUR, Mehmet Ali ÜSTÜNER, Ömer Faruk DİLMAÇ
      Abstract: Today, with the increase of industrialization, the waste heat emitted by the industrial machines used has started to increase. Therefore, the energy efficiency of these devices also decreases. In addition, this waste heat remains a bad factor that plays a role in the world's climate change. Governments are implementing incentive policies to increase energy efficiency and reduce greenhouse gas emissions. Therefore, both scientists and engineers strive for a cleaner environment and energy. Thermoelectric generators (TEGs) are one of the devices that contribute to energy efficiency and sustainable energy production by ensuring the recovery of a certain part of the waste heat emitted by these machines to the environment. The TEGs have found traditional uses from the waste heat of microprocessors to the waste heat of stoves. However, their proliferation is limited by their efficiency less than 10% and their high purchasing costs. Academicians and engineers continue to work without slowing down to overcome these. The semiconductors with low thermal conductivity and high electrical conductivity are the main subjects studied in this field. With overcoming these difficulties, it is aimed to use thermoelectric generators in the future to convert the waste heat of almost all devices into electrical energy. Therefore, the main purpose of this study is to investigate the current innovations of TEGs and to determine the future trend. Among the main findings of this study, it is predicted that TEGs will be widely used in areas where there is a need for silent and maintenance-free energy in the future.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • Energy Management with Intelligent Plug and Socket

    • Authors: Süleyman Hilmi YILMAZ; Edip TAŞKESEN, Khandan ROSHANAEI, Mehmet ÖZKAYMAK
      Abstract: Nowadays the devices that are used for electricity consumption by monitoring consumption values, and energy saving methods are supposed to identify and to develop them. To save the electricity people should know the consumption values of the devices and have idea about the consumed electricity. In this study, RFID technology, which is an automatic identification system, smart plug systems are used after recognizing the identity of the device information about the electricity consumption of that device. In this way, I directed the user to use electrical devices, which can be used when the electricity tariff is cheap so that the user could save money. For an average family, only the electricity consumption of the washing machine and dishwasher accounts for 30% of the total consumption. A family that uses a multi-time tariff will be able to save 10-15% by using the mentioned washing machine and dishwasher for example at night when the electricity tariff is low.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • Machine Learning Model to Diagnose Diabetes Type 2 Based on Health

    • Authors: Haithm ALSHARİ; Alper ODABAS
      Abstract: Diabetes, in 2016, was the 7th death-causing disease in the world. It was the direct cause of 1.6 million deaths. In 2019, the number of adults (20-79 years) that were living with diabetes was approximately 463 million and is expected to rise to 700 million in 2045. The early diagnosis of diabetes will help treat it and prevent its complications. The need for an easy and fast way to diagnose diabetes is crucial. In this study, we are proposing a method to diagnose diabetes with the help of machine learning algorithms and tools. The proposed method utilizes the power of machine learning to create a model that can predict diabetes based on the health behavior of the patient. The model uses the relationship between a healthy lifestyle and diabetes. Our goal is to build a reliable machine learning model to predict diabetes, which will help significantly in easing and speeding up the diagnosing procedure of diabetes. We used modern machine learning algorithms like XGBoost, LightGBM, CatBoost, and artificial neural networks, and the dataset was obtained from the National Health and Nutrition Examination Survey (NHANES). In our study, the XGBoost algorithm performed the best with a Cross-Validation (10-fold) score of 0.864, and an overall accuracy of 87.7% for the validation dataset and 84.96% for the test dataset. 
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • Effects of Cobalt Doping on the Structural, Optical, and Electrical
           Properties of SnO2 Nanostructures Synthesized by SILAR Method

    • Authors: Muhammed Emin GÜLDÜREN; Ahmet TAŞER, Harun GÜNEY
      Abstract: Undoped and cobalt (Co) doped tin oxide (SnO2) films were prepared onto glass slides via the successive ionic layer adsorption and reaction (SILAR). Variable characterization methods were applied to examine the effects of cobalt impurities on physical properties of SnO2 films. The performed characterization measurements were X-ray diffraction, Ultraviolet–visible spectrometer, Photoluminescence, and Raman. No peak ascribed to Co, SnO, or Sn was found in the XRD spectrum which may indicate the integration of cobalt in SnO2 crystal lattices. And the obtained XRD peaks may be related to the tetragonal rutile phase of pure SnO2. SEM images exposed that the Co dopant atoms affectedthe sample morphologies. The optical analyses showed that the transmittance and reflectance percentages dropped by the introduction of impurities to the SnO2 system as the absorbance values of doped SnO2 samples increased. Thus,a red shift (2.6–1.8 eV) occurred in the bandgapsas Co concentration changed in the films. The Raman spectra of pure SnO2 and Co:SnO2 samples exhibited major peaksaround 481 cm−1, 571 cm−1 and 602 cm−1. In photoluminescence spectrum, it was noted that the emission intensity can both increase or decrease due to the different cobalt doping ratios in the SnO2 nanostructures. Resistance measurements displayed that the resistivity increased with the increment of doping concentration. However, it was shown that the electrical conductivities could be increased after the heat treatment of glass substrates up to 500 oC, a common behavior of semiconductor materials.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • Fractal Dimension of Streetscape as a Proxy to the Design Dimension of the
           Built Environment in Walkability Research

    • Authors: Maghsoud GHANAT BARI; Ayse TEKEL
      Abstract: Multidisciplinary nature of walkability research accelerated its growth through the participation of different disciplines. Different methods of measurement and analysis from varying disciplines created disagreements about how to characterize the built environment dimensions by using appropriate attributes, especially attributes which are used to represent the design dimension of the built environment. Fractal dimension value of streetscape provides solutions to these arguments as it makes the use of both micro-scale and macro-scale attributes of the built environment, especially micro-scale attributes of its design dimension as it relates to the quality of walking. Walkability indices were created then validated by a survey conducted at Dutluk station in Keçiören, Ankara. Results show that using fractal dimension value of streetscape as a variable in the walkability index can identify the factors that influence walking behavior.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • Analyzing the Competition of HIV-1 Phenotypes with Quantum Game Theory

    • Authors: Bilge ÖZLÜER BAŞER
      Abstract: HIV-1 (Human Immunodeficiency Virus) is a virus that causes AIDS (Acquired Immunodeficiency Syndrome), which damages the immune system by reducing people's resistance to infections and diseases. Antiretroviral treatment methods are based on drug designs developed using inhibitors that suppress the dynamics that enable the maturation of the virus. However, studies are needed to improve treatment methods against infection because HIV-1 is frequently mutated and mutant viruses develop resistance to the treatment used. Therefore, it is important to model the evolutionary development of the virus. For this purpose, the developmental process and spread of HIV-1 are modeled as a game with the players of phenotypes in this study. The related searches known to be made so far have been carried out based on the rules of classical physics. However, games of survival are being played on the molecular level, where the rules of quantum mechanics work. Since the HIV-1 game is being played on the molecular level, the behaviors of the virus phenotypes are examined from the perspective of quantum computation.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • A Miniaturized Multi-layer Microstrip Antenna for Linear Wireless Sensor
           Network Monitoring Systems

    • Authors: Mohamed BENZAGHTA; Burak ER, Gulsima BİLGİN, Elif AYDIN, Ali KARA
      Abstract: This article presents a sub-GHz ISM band microstrip patch antenna based on the use of multi-layer compact structure, which overcomes the shortcomings of typical microstrip antennas such as low gain and high resonant frequency. The antenna was simulated using an electromagnetic simulator, ANSYS HFSS, and fabricated on two different substrates: RT Duroid 5880 and FR4 epoxy with a compact size of 100 x 100 x 8 mm3 (0.29λ × 0.29λ × 0.02λ). The simulated results of the antenna were then compared with the measured ones, and the two were observed to have a reasonable agreement. The proposed antenna operates in the sub-GHz license-free ISM band (862-875 MHz), with a gain value of 2.92 dB. Two prototypes of the proposed antenna were fabricated and used in a Linear Wireless Sensor Networks (LWSNs) monitoring system. Results show that the proposed antenna is a good candidate for those types of LWSNs systems.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • Scheduling and Rostering of Temporary Staff to Deal with Periodically
           Increasing Demand in Retail Sector: An Application

    • Authors: Ahmet CÜREBAL; Serkan KOÇTEPE, Tamer EREN, Emir Hüseyin ÖZDER
      Abstract: Temporary employment is a need to meet periodically increasing demand. It is arranged for a limited number of days and its service quality output is observed instantly. These make the planning phase complicated. In the process, the priority of businesses is to meet the increasing demand and to regulate the workload according to the terms of the period. Solving the periodic increase in demand by providing permanent employment can cause businesses to face the costs arising from excess employment in the long term. Generally, businesses manage these periods by hiring new staff. The most critical problems of the process are the suitability of the temporarily employed staff to work and whether they are suitable for the competencies in the job description. It is expected to achieve an efficiency equivalent to the cost to be incurred for this need that occurs in certain time periods. Adaptation processes, the effects of today's pandemic virus, and ergonomics issues owing to some tasks are the other basic constraints of this planning process. In this study, the problem of scheduling and rostering of staff requested for the problem of staff shortage owing to periodically increased demand has been solved. 50 candidate staff were evaluated in 4 competency types. Thus, an optimized service quality and staff costs has been achieved for this periodic staff need. For problem solving, 0-1 integer programming model was established and the proposed model, is written in ILOG CPLEX Studio IDE and is solved with the CPLEX solvent.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • Investigation of the Series Hybrid Electric Powertrain Architecture with
           Wankel Engine as a Range Extender

    • Authors: Anılcan ÖZKAN; Hikmet ARSLAN, Osman Taha ŞEN
      Abstract: In this study, a conventional vehicle is converted into a series hybrid electric vehicle. Electric motor power, battery pack capacity, range extender operating condition is determined; a computational model of the vehicle is built and simulations are conducted using Worldwide Harmonized Light Vehicles Test Procedure (WLTP). Power rating of the electric motor is calculated as 120 kW for the same acceleration performance. Wankel engine data available in the Automotive Laboratory of Istanbul Technical University are used. Energy capacity of battery pack is determined according to the daily driving distance of the WLTP. Engine on-off control strategy is used to control range extender operation. Wankel engine is operated at a speed of 4000 rpm and load of 5.15 bar, hence it is tuned to deliver an output power of 22.3 kW. Simulation results show that the performance of Wankel engine is validated as range extender by using engine on-off control strategy. State of charge of battery pack is set as minimum (30%) at the beginning of simulation and the state of charge of the battery pack charged by the range extender is assumed to be approximately 50% at the end of the cycle. For comparison, performance of Wankel engine is compared to the range extender of a mass-produced series hybrid electric vehicle, which has a battery pack capacity of 18.8 kWh. In conclusion, it is shown that a more compact range extender unit with a battery pack of 35 kWh is advantageous from the perspective of the packaging of the battery pack.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • Homotopy Perturbation Elzaki Transform Method for Obtaining the
           Approximate Solutions of the Random Partial Differential Equations

    • Authors: Halil ANAÇ; Mehmet MERDAN, Tülay KESEMEN
      Abstract: The series solutions of the random nonlinear partial differential equations have been examined by a hybrid method. The random nonlinear partial differential equations are studied by both normal and uniform distributions. Two initial-value problems are indicated to exemplify the influence of the solutions acquired by the hybrid method. Also, the functions for the first and second moments of the approximate solutions of random nonlinear partial differential equations are acquired in the MAPLE software. The hybrid method is implemented to analyze the solutions of the random nonlinear partial differential equations. MAPLE software is used to find the solutions. Besides, MAPLE software is used for the drawing the figures.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • Synthesis and Characterisation of Sugarcane Bagasse and Pineapple Leaf
           Particulate Reinforced Polyester Resin Matrix Composites

    • Authors: Babatunde BOLASODUN; Stephen DUROWAYE, Theddeus AKANO
      Abstract: In this study, an experimental research was conducted in developing and characterising sugarcane bagasse and pineapple leaf particulate particulate reınforced polyester resın composıtes. Unsaturated polyester resin (UPR) was reinforced with sugarcane bagasse and pineapple leaf particulates in varied proportions (0 – 25 wt. %) by mould casting. Morphology and mechanical properties of the composites were examined. There was a good dispersion of particulates in the polyester resin. The sugarcane bagasse reinforced composite demonstrated the highest tensile strength, flexural strength, and impact energy of 84.94 MPa, 121.16 MPa, and 7.37 J respectively at 20 wt. % reinforcement. The tensile strength, flexural strength, and impact energy of the composites improved with increasing concentration of the reinforcement. This is an indication of the suitability of the reinforcing materials as fillers for unsaturated polyester resin and an indication of the potential the polymer matrix composite has for low strength applications.   
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • Money Laundering Detection with Node2Vec

    • Authors: Mehmet ÇAĞLAYAN; Şerif BAHTİYAR
      Abstract: The widespread use of computing technology has been changing relationships among people in societies. Criminals are aware of the power of the technology so that many criminal activities involve more computing systems. Money laundering has been a significant criminal activity within financial computing systems for many decades. The dynamic nature of information systems has reduced the effectiveness of existing money laundering detection mechanisms that is an important challenge for societies. In this paper, we consider machine learning algorithms as complementary solutions to existing money laundering detection mechanisms. We have focused on graph-based representation of data with Node2Vec to have better classification results for money laundering detections with machine learning algorithms. Our experimental analyses show that Node2Vec enable us to select the most convenient machine learning algorithm for money laundering detections.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • Using Long-Short Term Memory Networks with Genetic Algorithm to Predict
           Engine Condition

    • Authors: Semra ERPOLAT TAŞABAT; Olgun AYDIN
      Abstract: Predictive maintenance (PdM) is a type of approach for maintenance processes, allowing maintenance actions to be managed depending on the machine's current condition. Maintenance is therefore carried out before failures occur. The approach doesn’t only help avoid abrupt failures but also helps lower maintenance cost and provides possibilities to manufacturers to manage maintenance budgets in a more efficient way. A new deep neural network (DNN) architecture proposed in this study intends to bring a different approach to the predictive maintenance domain. There is an input layer in this architecture, a Long-Short term memory (LSTM) layer, a dropout layer (DO) followed by an LSTM layer, a hidden layer, and an output layer. The number of epochs used in the architecture and the batch size was determined using the Genetic Algorithm (GA). The activation function used after the output layer, DO ratio, and optimization algorithm optimizes loss function determined by using grid search (GS). This approach brings a different perspective to the literature for finding optimum parameters of LSTM. The neural network and hyperparameter optimization approach proposed in this study performs much better than existent studies regarding LSTM network usage for predictive maintenance purposes.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • Unit Commitment Problem with Emission Cost Constraints by Using Genetic

    • Authors: Mehmet YILDIRIM; Mustafa ÖZCAN
      Abstract: A power system’s operating cost needs to be minimized by satisfying varying load demand while taking into account the prevailing constraints in a multiple unit electrical power system. In this study, by using genetic algorithms (GA), a short-term thermal unit commitment problem was solved and an economical generating unit schedule was made with the solution obtained. Taking into account the negative effects of emissions due to the use of fossil fuels, emission costs were added to the objective function together with fuel and start-up costs. The GA chromosome structure was formed by binary encoding, new generations were selected by roulette wheel selection mechanism and single point crossover was applied. The representation, formulation and the simulation results of the problem for a 5-unit test system during the scheduling hours of the period are presented. The number and the operating hours of the generating units to be committed were determined by satisfying the prevailing constraints. During the planning period, 13360 MW of power demand was met by 755 MW of spinning reserve. Total operating cost was calculated as $430330. Of the total operating cost, 32% consists of emission costs.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • Temperature Waves Phase Optimal Time Lag in the Refrigerated Warehouse
           Thermal Insulation

    • Authors: Yurii MYRONCHUK; Mykhailo KHMELNİUK
      Abstract: The thermal inertia of the wall manifests itself as a damping of amplitude (Decrement Factor) as well as a temperature wave phase lag (Time Lag) upon its passing through the wall. The objective of the research was to highlight the utilization prospects of these phenomena in the building envelops of large refrigerated warehouses. Numerical methods were used for nonlinear, non-stationary processes simulation. The relationship of the refrigeration cycle to the thermo-insulating walls of the cold store in the conditions of daily external temperature oscillations and solar radiation flux has been studied. As the ambient temperature rises, the power efficiency of the refrigeration cycle is decreasing and the need to increase the compressor displacement is growing. If the value of the phase delay in the wall is optimum, the daily minimum of the heat leakage through the wall enters the chamber with the phase shift for the period of maximum daily external temperature. This enables to smooth out the daily oscillations amplitudes of the heat load of the refrigerating machine as well as compressor power rating and to approximate their peak values closer to the average daily ones. The study had been concluded by demonstrating the possibility of reduction in: heat exchange areas for both condenser and evaporator, receiver volume, diameter of pipelines, material cost. Better conditions for temperature stabilization in the cold store will enhance the keeping quality and prolong the food products shelf life.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • Sustainable Management of a Renewable Fishery Resource with Depensation
           Dynamics from a Control Systems Perspective

    • Authors: Oğuzhan ÇİFDALÖZ
      Abstract: Human societies are exploiting natural renewable sources such as fisheries, forests, groundwater basins, rivers, and soil at an increasing intensity. Around the world, these resources are being managed by various institutions or governments. One of the challenges faced by institutions is to develop strategies and policies to effectively manage these renewable resources under social and ecological uncertainties, disturbances, policy implementation difficulties, and measurement errors. In this paper, a fishery is considered as an example and the problem of managing a fishery is approached from a control systems perspective. The justification behind this approach is due to the observation that the problem of managing a renewable resource can be posed as a control systems problem and that the discipline of control systems possesses tools and methods to deal with model uncertainties, external disturbances, measurement errors and implementation issues. For the fishery, a depensation type population dynamics model is considered. Depensatory models are used in social/ecological systems in order to model dynamics of certain species of fish populations. An optimal control strategy based on Pontryagin’s Maximum Principle is derived and its sustainability and robustness properties with respect to parametric uncertainties, measurement errors and disturbances are examined. Finally, a sub-optimal but more robust control strategy is proposed and its robustness properties are provided. The main objective of the paper is to show that a control systems engineering approach can be applied to a social-ecological problem and it can provide easy to implement management strategies, insight, and guidance into the management of renewable resources. 
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • Comparative Study of Symbolic Motifs of Peacock and Simurgh in Selected
           Historical Monuments of the Safavid Period in Ardabil and Isfahan Cities

    • Authors: Roya ESMİ; Habib SHAHBAZİ SHİRAN
      Abstract: The symbolic motifs of birds in historical monuments are an embodiment of religious concepts and ancient myths and express the rich mystical content, human aspirations and desires through its historical period. Therefore, this study seeks to examine the commonalities or differences between the location, number and interpretations of bird motifs (Simurgh and Peacock) at the beginning and the end of the Safavid dynasty, in selected monuments of the cities of Ardabil (Sheikh Safi al-Din Ardabili’s Khānegāh and the tomb of Sheikh Amin al-Din Jabrail) and Isfahan (Shah Mosque, Hasht Behesht Palace, Chahār Bāgh school and Emamzadeh Haroun-e-Velayat). In this study, field method and content and historical analysis of information sources and documents were used. The analysis showed that most of the Peacock and Simurgh motifs are found in the monuments of Ardabil, in the interior and exterior spaces, and in the selected monuments of Isfahan, mostly in the exterior spaces, facaded and entrance gates. The Peacock bird motifs in the monuments of Ardabil city, probably refers more to deep mysticism, perishing in God, spirituality and inner purity, but in the monuments of Isfahan city, the Peacock motifs often serves as a gatekeeper and guiding people toward heaven and repelling the devil. Also, Simurgh's motifs in the historical monuments of Ardabil city seem to be somewhat reminiscent of unity in plurality, a symbol of the essence of transcendence, perfect man and divinity; However, in the historical monuments of Isfahan, it often refers to the conflicting concepts of the human soul, which includes Ahura Mazda and Ahriman, and indicates man's attempt to overcome his own soul.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • ARM MCU-Based Experimental EEG Signal Generator Using Internal DAC and PWM

    • Authors: Ertuğrul KARAKULAK
      Abstract: Electrophysiological signal generators are widely used in biomedical engineering research, biomedical education and the testing of devices in hospitals. Such signal generators are also available commercially. The EEG (Electroencephalography) signal is an electrophysiological signal which is emitted from the brain. In this study, a signal generator that produces experimental EEG signals taken from databases is proposed. The proposed signal generator reads the experimental data from an SD card with SDIO serial protocol. In addition, the PWM and DAC outputs of the microcontroller are used and examined separately to generate the signal. It has been shown that the experimental signals taken from the database can be generated by using cheap and easily accessible electronic devices.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • Performance Analysis of Line-Start Concentrated Dual-winding Synchronous
           Reluctance Machine with Capacitive Assistance

    • Authors: Ayebatonye EPEMU; Donatus ONYİSHİ, Simon OBE
      Abstract: The transient and dynamic performance analysis of a proposed line-start, three-phase concentrated dual-winding synchronous reluctance motor (cDWSynRM) in comparison with the conventional concentrated winding synchronous reluctance motor (cSynRM) was presented. Both windings are overlapping windings. The cDWSynRM consist of main and auxiliary windings with capacitive assistance for power factor improvement. The modelling of the synchronous reluctance motors (SynRM) was done in direct-phase variables considering only the fundamental magneto-motive force (MMF). The machine inductances of both machine models were determined using winding function theory (WFT). These derived inductances were used to determine machine performance characteristics such as Torque, Speed, Phase currents etc. The performance characteristics of both motors were monitored using MATLAB/Simulink, and the proposed line-start cDWSynRM with capacitive assistance was observed to have improved performance characteristics when compared to the cSynRM.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • A Hybrid Time Series Prediction Model Based on Fuzzy Time Series and
           Maximal Overlap Discrete Wavelet Transform

    • Authors: Nevin GÜLER DİNCER; Muhammet Oğuzhan YALÇIN, Öznur İŞÇİ GÜNERİ
      Abstract: This study proposes a new time series prediction method that combines Fuzzy Time Series (FTS) based on fuzzy clustering and Maximal Overlap Discrete Wavelet Transform (MODWT). Time series generally consist of subseries, each of which reflects the different behavior of the time series and using of a single prediction method for all subseries can be negatively impacted the prediction and forecasting accuracy. Proposed method is based on decomposing of time series into sub-time series through MODWT and predicting an FTS model for each sub-time series separately. Besides, time series can contain noise, outlier or unwanted data points and these points can hide the actual behavior of the time series. MODWT has the ability of eliminating negative effects of these kind of data points on the predictions. Besides, proposed method has also all advantages of FTS methods. The main objective of this study based on these advantages is to improve the prediction and forecasting performance of existing FTS methods based on fuzzy clustering. In order to show the performance of proposed method, three FTS methods based on fuzzy clustering and wavelet-based versions of them are applied to eight real time series and experimental results clearly showed that proposed method achieves the best prediction and forecasting results.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • The Related Study Tendencies in the Field of Gasification: A Bibliometric

    • Authors: Sertac Samed SEYITOGLU; Ali KILIÇARSLAN
      Abstract: Undoubtedly, energy plays a vital role in every sphere of life. Fossil energy sources such as coal and natural gas are generally used for energy production. People are looking for more efficient use of the source in recent years due to the rapid depletion in the fossil fuel resources. Gasification of coal is a useful method for produce clean and efficient energy. This study was carried out to find out the various trends in scientific studies that provide literature for the field of coal gasification on world. All data used in this study have been reached from Web of Science database. In this study, the coal gasification related to both bibliometric and historical analyses were investigated. The Web of Science database was scanned for the articles about coal gasification between the years of 1989 and 2020. The considered parameters in the bibliometric analysis are the number of citations and documents, authorships and ownerships, patterns of international collaborations and addresses.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • Modeling Rheological Behavior of Beef based on Time-Dependent Deformation
           and Packaging

    • Authors: Adeshina FADEYİBİ
      Abstract: Modeling of food deformation behavior is vital for structural characterization. This research was undertaken to study the rheological properties of beef by developing mathematical models for different packaging and temperature conditions. The rheological properties of the beef sample, packaged in a polyethylene (LD and HD) and aluminum foil (A foil), were determined experimentally at -20oC and 5oC for 0‒ 60 days. Power law, Herschel-Bulkley and Tiu-Boger theories, formulated for a period-dependent deformation, were used to constitute the models. Results show that the deformation index varies in the range of 1< n< 3, indicating a nonNewtonian shear thickening behavior. Also, a better estimation of the deformation consistency, k was obtained using the Tiu-Boger theory for the A. Foil at 5oC and Herschel-Bulkley theory for the LD at -20oC. The models are significant with MSE <5% and R2 > 85%, suggesting their suitability for industrial scale-up prediction.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • Classification of 8-dimensional Nilsolitons by Symbolic Computation

    • Authors: Hülya KADIOĞLU
      Abstract: In this paper, we develop an algorithm to classify 8 dimensional nilsolitons with simple nilsoliton derivation. We restrict our classifications to the nilsolitons corresponding to singular Gram matrix with nullity 1-3. This work can be considered as a continuation paper to our previous study where we introduced a procedure to classify algebras in dimension 8 that admit simple derivations and singular Gram matrices U. Having the singular Gram matrices, there exists infinitely many solutions to Uv =[1]_m , where the solutions are exactly the squares of the structure constants. Also, the structure constants have to satisfy the Jacobi identity for the algebra to be a Lie algebra. In our previous work, we did not introduce a procedure to create and solve the Jacobi identity(s). In this study, we take care of this issue by using computer algorithms for each index set. Thus, we complete classification of all 8 dimensional in-decomposable nilsolitons with the nullity of corresponding Gram matrix is in the set {0,1,2,3}. We provide several examples to illustrate the algorithm. For the implementation process of the newly introduced algorithm, we use MATLAB R2020b.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • Alpha Power Odd Generalized Exponential Family of Distributions: Model,
           Properties and Applications

    • Authors: Ibrahim ELBATAL; Selen ÇAKMAKYAPAN, Gamze ÖZEL
      Abstract: In this paper, we exhibit a general family of distributions called alpha power odd generalized exponential family of distributions. The new family is very flexible with increasing, decreasing, J, reversed-J, bathtub shapes. Statistical properties of the family such as quantile, expansion of density function, moments, incomplete moments, mean deviation, Bonferroni and Lorenz curves are proposed. The method of maximum likelihood to estimate the model parameters is used. Three applications based on real data sets are the importance and flexibility of the three proposed models.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • Chemical and Electrochemical Study of Effect of Soluble Sulfonated
           Polystyrene on Mild Steel Interface in Hydrochloric Acid Solution

    • Authors: Abhishek DWİVEDİ; Prem BHARTİ, Sudhish Kumar SHUKLA
      Abstract: The author has focused on the corrosive effect of 0.14% carbon steel in the occurrence of several amounts of soluble Sulfonated Polystyrene (SPS) and was found to be best efficient on soft iron exterior at 100ppm concentration in 0.5M hydrochloric acid assortment at 298K heat during 3h of time in this paper. The examination was performed by studying the weight loss of mild steel by varying different parameters like mixture concentration, time, and solution temperature. The efficiency of SPS was observed to rise with an increase of 91.90% of an inhibitor in the acid solution. The mechanism of physical adsorption was studied to the initiation and permitted dynamics for the reaction of altitude and extracted taking place towards the exterior of the iron sample in endothermic, impulsive and dependable through the Langmuir isotherm adsorption. Anodic and cathodic both type of nature of soluble SPS was studied using the potentiodynamic polarization method. The AFM analysis was used to do the surface and protective film analysis and under varied settings, SPS polymer inhibitor proven to be more suited for iron metal exterior.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • New Advances on Fuzzy Linear Programming Problem by Semi-Infinite
           Programming Approach

    • Authors: Hadi ZAVİEH; Hadi NASSERI, Chefi TRIKI
      Abstract: As we are faced with more uncertainty problems in the real world, it is necessary to ‎provide ‎models that can provide appropriate solutions for dealing with these issues. In this ‎study, we ‎ proposed a new approach to solving linear programming problem in the fuzzy ‎environment ‎based on solving ‎a related multi-objective model. This kind of problem can be ‎reduced to a ‎fuzzy linear semi-infinite programming problem. In this way, we present a new ‎mixed ‎Multi-Objective Linear Semi-Infinite Programming (MOLSIP) model to solve the ‎main ‎problem, furthermore, as a practical case, we consider a fuzzy Data Envelopment ‎Analysis ‎‎(DEA) model which is a concern to‎ an evaluation of the performance of Decision-‎Making ‎Units (DMUs) in uncertainty environment, The new models show the advantage of ‎our ‎method over the previous ones in terms of certainty. Finally, numerical examples ‎are ‎included to illustrate the suggested solution procedure.‎
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • Comparison of Hot-rolled Unalloyed Magnesium and Magnesium Alloys in terms
           of Biodegradability and Mechanical Properties

    • Authors: Alper İNCESU; Ali GÜNGÖR
      Abstract: In this study, hot rolling is properly performed on pure magnesium and two of Zn, Ca and Mn containing magnesium alloys. Biodegradability and mechanical properties are investigated comparatively in their rolled state. While the average grain sizes of the two alloys were close to each other, it was observed that the Mg-1.01Zn-1.63Ca-0.30Mn alloy had higher hardness (61.5 ± 0.2 HV) at hot rolled state. The lowest corrosion rate in electrochemical corrosion test on Mg-1.07Zn-0.21Ca-0.31Mn alloy is observed to be 1.772 mm/yr. As for the immersion corrosion test on the same alloy, the lowest corrosion rate is detected to be 0.054 mm/yr. Moreover, Mg-1.07Zn-0.21Ca-0.31Mn alloy has the highest tensile strength. Based on the results, it is ascertained that hot-rolled Mg-1.07Zn-0.21Ca-0.31Mn alloy possesses a better biodegradability and mechanical properties compared to hot rolled commercially unalloyed Mg and 1.01Zn-1.63Ca-0.30Mn alloy.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
  • The Current-Voltage Characteristics for Electrode Geometry Model of
           Positive DC Corona Discharge in Air

    • Authors: Asep Yoyo WARDAYA; Zaenul MUHLİSİN, Jatmiko Endro SUSENO, Muhammad NUR, Pandji TRİADYAKSA, Ali KHUMAENİ, Eko SARWOKO, Jaka WİNDARTA, Susilo HADİ
      Abstract: Research on corona plasma discharges from plasma reactors has been carried out using the Point and Semicircular-Plane (PSC-P) electrode configuration in the air. The purpose of this study is to compare the suitability level of the current-voltage (I-V) characteristics curve from the results of experimental data and numerical simulation calculations of the electrode geometry function based on the variation of three electrode configuration sizes (small plate, medium plate, and large plate) and two variations of the distance between the two electrodes in each electrode configuration size. The results of the study prove that there is a high degree of conformity between numerical calculations with experimental data through calculations from the Python GUI Programming by taking a fitting value from the certain k-shape sharpness factor. The calculation location of the k-shape sharpness factor lies on the electrode tip sharp surface which will produce the largest plasma flow in the plasma reactor equipment.
      PubDate: Thu, 01 Sep 2022 00:00:00 +030
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