Detection of Rotor Bar Faults in Field Oriented Controlled Induction Motors

Akar, Mehmet The Korean Institute of Power Electronics 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.6

In this study, a new method has been presented for the detection of broken rotor bar (BRB) faults in inverter driven induction motors controlled via Field Oriented Control (FOC). To this end, a FOC controlled induction motor with a BRB fault was modeled using the Matlab/Simulink program. Experiments were carried out using the prepared simulation model at various loads and operating speeds. The motor current and speeds were monitored for healthy, 1, 2 and 3 BRB faults. The Resampling Based Order Tracking Analysis (RB-OTA) method was applied to the monitored signals. The obtained results were compared by using the classic Fast Fourier Transform (FFT) method. When the obtained results were analyzed via the FFT method no information regarding any faults was determined in the run up or run down regions of the motor and the presented method gave very good results. The reliability of the proposed method was validated with experimental results. The main innovative part of this study is that the RB-OTA method was implemented on the induction motor current signal for detecting BRB faults.

Influence of carbon nanotube inclusions to electrical, thermal, physical and mechanical behaviors of carbon-fiber-reinforced ABS composites

Akar Alinda Oyku,Yildiz Umit Hakan,Tirkes Seha,Tayfun Umit,Hacivelioglu Ferda 한국탄소학회 2022 Carbon Letters Vol.32 No.4

Acrylonitrile–butadiene–styrene (ABS) terpolymer was compounded with short carbon fiber (CF) and carbon nanotube (CNT) using a micro-extruder followed by the injection molding process. Composite samples were fabricated with loading ratios of 20 wt.% CF and 0.1, 0.5 and 1.0 wt.% of CNT. Mechanical, electrical, thermo-mechanical, thermal, melt-flow, and structural investigations of ABS-based composites were conducted by performing tensile, impact, hardness, and wear tests, conductive atomic force microscopy (AFM), dynamic mechanical analysis (DMA), thermal gravimetric analysis (TGA), melt flow rate test (MFR), scanning electron microscopy (SEM) characterization techniques, respectively. According to mechanical test data of resultant composites including tensile and impact test findings, CNT additions led to the remarkable increase in tensile strength and impact resistance for CF reinforced ABS composites. The formation of synergy between CNT nanoparticles and CF was confirmed by electrical conduction results. The conductive path in ABS/CF composite system was achieved by the incorporation of CNT with different loading levels. SEM micrographs of composites proved that CNT nanoparticles exhibited homogeneous dispersion into ABS matrix for lower loadings.

Detection of Rotor Bar Faults in Field Oriented Controlled Induction Motors

Mehmet Akar 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.6

In this study, a new method has been presented for the detection of broken rotor bar (BRB) faults in inverter driven induction motors controlled via Field Oriented Control (FOC). To this end, a FOC controlled induction motor with a BRB fault was modeled using the Matlab/Simulink program. Experiments were carried out using the prepared simulation model at various loads and operating speeds. The motor current and speeds were monitored for healthy, 1, 2 and 3 BRB faults. The Resampling Based Order Tracking Analysis (RB-OTA) method was applied to the monitored signals. The obtained results were compared by using the classic Fast Fourier Transform (FFT) method. When the obtained results were analyzed via the FFT method no information regarding any faults was determined in the run up or run down regions of the motor and the presented method gave very good results. The reliability of the proposed method was validated with experimental results. The main innovative part of this study is that the RB-OTA method was implemented on the induction motor current signal for detecting BRB faults.

Globalization and its challenges for developing countries: the case of Turkish higher education

Hanife Akar 서울대학교 교육연구소 2010 Asia Pacific Education Review Vol.11 No.3

This paper examines the challenges faced by the Turkish higher education system and exposes the inequities and realities educators in a developing nation must struggle with as they try to find a prestigious spot in the knowledge-production industry. After a brief overview of the literature that illustrates how globalization penetrated into each stage of development of Turkey's modern institutions of higher education, the paper presents a discussion, based on national and international statistics, of the challenges these institutions face as a result of globalization, namely increasing demands for higher education; faculty shortages; the internationalization of higher education; research and knowledge production; and the process of financing higher education.

Analyzing Factors Affecting the Adoption of Cloud Computing: A Case of Turkey

( Ezgi Akar ),( Sona Mardikyan ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.1

Cloud computing is an upcoming technology and emerging concept in the field of information technologies. Companies have begun to invest in cloud computing with the expectation that it will improve their business performances, operations, and processes. However, many companies are not so much aware of the cloud computing, so they can hesitate to adopt this new technology. The aims of the study are analyzing factors affecting the adoption of cloud computing and applying structural equation modeling technique to analyze the important dimensions of the adoption. Concordantly, previous studies are examined and expert interviews are arranged. Based on both our literature review and expert interviews, a model is proposed to measure the adoption of cloud computing. It is obvious that there are scarce researches about cloud computing adoption in the literature. Thus, the originality of the paper lies on that it proposes a research model for cloud computing adoption and it investigates various dimensions of cloud computing adoption in detail.

Design of Self-Starting Hybrid Axial Flux Permanent Magnet Synchronous Motor Connected Directly to Line

Eker, Mustafa,Akar, Mehmet,Emeksiz, Cem,Dogan, Zafer,Fenercioglu, Ahmet The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.5

In view of the current state of the reserves of electric energy generated resources and the share of electric motors in electricity consumption, many researches and studies related to efficiency in electric motors are being made. The presented work is related to the Axial Flux Permanent Magnet Synchronous Motor (AF-PMSM), which has recently undergone significant work based on the development of magnet and motor technology. In this study, a novel AF-PMSM was designed analytically through Finite Element Method (FEM) which can be started by connecting to a line such as an asynchronous motor in a transient state and can operate with high efficiency and power factor after synchronization in steady state without the need for an expensive motor drive. According to the obtained FEM results, a design with an efficiency class of IE4 of 5.5 kW shaft power, a 4 poles motor was obtained. As a result, economic calculations indicate that the extra cost of the designed Line start AF-PMSM with respect to the asynchronous motor is rapidly compensated by energy saving due to a more efficient operation, especially constant speed operations. As a result of the analysis obtained, the targeted values are reached. For induction motors and radial flux permanent magnet synchronous motors, a good alternative motor that can operate with high efficiency and power factor has been obtained.

Cancer Pain Prevalence and its Management

Arslan, Deniz,Koca, Timur,Akar, Emre,Tural, Deniz,Ozdogan, Mustafa Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.20

Pain is a public health problem affecting more than half of cancer patients. Despite the success of the protocols currently used, pain cannot still be reduced satisfactorily in the large majority of patients. In order to improve pain management, all healthcare professionals involved with pain should have sufficient knowledge on pain assessment and treatment, and should inform patients to prevent patient-related barriers. In this compilation, the prevalence values and the treatment methods of cancer pain, and the barriers to pain management have been assessed.

Design of Self-Starting Hybrid Axial Flux Permanent Magnet Synchronous Motor Connected Directly to Line

Mustafa Eker,Mehmet Akar,Cem Emeksiz,Zafer Dogan,Ahmet Fenercioglu 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.5

In view of the current state of the reserves of electric energy generated resources and the share of electric motors in electricity consumption, many researches and studies related to efficiency in electric motors are being made. The presented work is related to the Axial Flux Permanent Magnet Synchronous Motor (AF-PMSM), which has recently undergone significant work based on the development of magnet and motor technology. In this study, a novel AF-PMSM was designed analytically through Finite Element Method (FEM) which can be started by connecting to a line such as an asynchronous motor in a transient state and can operate with high efficiency and power factor after synchronization in steady state without the need for an expensive motor drive. According to the obtained FEM results, a design with an efficiency class of IE4 of 5.5 kW shaft power, a 4 poles motor was obtained. As a result, economic calculations indicate that the extra cost of the designed Line start AF-PMSM with respect to the asynchronous motor is rapidly compensated by energy saving due to a more efficient operation, especially constant speed operations. As a result of the analysis obtained, the targeted values are reached. For induction motors and radial flux permanent magnet synchronous motors, a good alternative motor that can operate with high efficiency and power factor has been obtained.

A Simultaneous Analytical Method for Duplex Identification of Porcine and Horse in the Meat Products by EvaGreen based Real-time PCR

Sakalar, Ergun,Ergun, Seyma Ozcirak,Akar, Emine Korean Society for Food Science of Animal Resource 2015 한국축산식품학회지 Vol.35 No.3

A duplex real-time polymerase chain reaction (PCR) based assay for the detection of porcine and horse meat in sausages was designed by using EvaGreen fluorescent dye. Primers were selected from mitochondrial 12S rRNA and 16S rRNA genes which are powerful regions for identification of horse and porcine meat. DNA from reference samples and industrial products was successfully extracted using the GIDAGEN® Multi-Fast DNA Isolation Kit. Genomes were identified based on their specific melting peaks (Mp) which are 82.5℃ and 78℃ for horse and porcine, respectively. The assay used in this study allowed the detection of as little as 0.0001% level of horse meat and 0.001% level of porcine meat in the experimental admixtures. These findings indicate that EvaGreen based duplex realtime PCR is a potentially sensitive, reliable, rapid and accurate assay for the detection of meat species adulterated with porcine and horse meats.

A Simultaneous Analytical Method for Duplex Identification of Porcine and Horse in the Meat Products by EvaGreen based Real-time PCR

Ergun Sakalar,Seyma Özçirak Ergün,Emine Akar 한국축산식품학회 2015 한국축산식품학회지 Vol.35 No.3

A duplex real-time polymerase chain reaction (PCR) based assay for the detection of porcine and horse meat in sausages was designed by using EvaGreen fluorescent dye. Primers were selected from mitochondrial 12S rRNA and 16S rRNA genes which are powerful regions for identification of horse and porcine meat. DNA from reference samples and industrial products was successfully extracted using the GIDAGEN® Multi-Fast DNA Isolation Kit. Genomes were identified based on their specific melting peaks (Mp) which are 82.5°C and 78°C for horse and porcine, respectively. The assay used in this study allowed the detection of as little as 0.0001% level of horse meat and 0.001% level of porcine meat in the experimental admixtures. These findings indicate that EvaGreen based duplex real- time PCR is a potentially sensitive, reliable, rapid and accurate assay for the detection of meat species adulterated with porcine and horse meats.