Vibration and motor current analysis of induction motors to diagnose mechanical faults

Electric motors play an important role in industry, and the induction motors are the most widely used among them. Any motor failure interrupts the process, causes loss of productivity, and may also damages to other machinery. Therefore, to prevent sudden failure of motor (such as on the large or critical motor) it is essential to have an early fault detection mechanism. The work presented in this paper is concerned with the detection of the mechanical faults in three phased induction motors. Motor current signal analysis (MCSA) is used in identification of artificially induced mechanical faults, and it is also supported with vibration signal analysis. The most common mechanical problems; mechanical unbalance, shaft misalignment, and bearing failures are investigated experimentally. The efficacy of MCSA based monitoring for the detection of mechanical faults is demonstrated. Matlab based an automatic peak detection algorithm is also used in this study for determination of changes in signal spectrums

The Effect of Science Teaching Based on POE Strategy on the Academic Achievement and Attitudes of Fifth-Grade Students in the Distance Education Process

The aim of this study is to examine the effect of science teaching based on POE (Predict-Observe-Explain) technique on the academic achievement and attitudes of fifth-grade students in the distance education process. The study was carried out with the quasi-experimental design of quantitative research methods and an approach in which pretest and posttest applications were applied to the experimental and control groups. The research sample consists of 72 fifth grade students, 36 of whom are in the experimental group and 36 in the control group. Data collection tools included an academic achievement test and an attitude scale regarding learning science. The collected data were analyzed with the SPSS package program. The research results concluded that science teaching based on online POE technique increased the students’ academic achievement. Meanwhile, the attitude towards science learning was independent from teaching based on POE strategy

Effect of arc re-melting on microstructure, mechanical and tribological properties of commercial 390A alloy

To investigate the effect of the arc re-melting on the microstructure, mechanical and tribological properties of the 390A alloy, its ingot produced by the conventional induction melting method was subjected to the arc re-melting process. The microstructure of the 390A alloy was examined by OM and SEM. Mechanical properties of the 390A alloy were determined by the Brinell method and tensile tests. Tribological properties were investigated with a ball-on-disc type tester. It was observed that the microstructure of both conventional induction melted and arc re-melted 390A alloys consisted of alpha(Al), eutectic Al-12Si, primary silicon particles, theta-CuAl2, beta-Al5FeSi, delta-Al4FeSi2, and alpha-Al-15(FeMnCu)(3)Si-2 phases. Re-melting with the arc process caused grain refinement in these phases. In addition, after this process, the alpha(Al) phase and primary silicon particles were dispersed more uniformly, and sharp edges of primary silicon particles became round. The arc re-melting process resulted in an increase in the hardness of the 390A alloy produced by the conventional method from 102 HB to 118 HB and the tensile strength from 130 to 240 MPa. It also caused an increase in the wear resistance of the 390A alloy and a decrease in the friction coefficien

Determining science teacher candidates’ comprehension level of equations

It is commonly known that mathematics is used in many subjects in physics and chemistry courses and the relations between mathematics and variables are more easily understood. These courses also comprise a number of equations that correspond to a mathematical correlation and are also called formulas. Therefore, the aim of the present study is to determine the level of science teachers to verbally express the meaning of the equations given and comprehension of the mathematical structure of equations. The data obtained with the help of open-ended questions were analyzed by the content analysis method, one of the qualitative research methods. According to the data obtained, code, category and themes were created. The study was carried out with science teacher candidates studying at the Faculty of Education of Bursa Uludağ University in the 2017 and 2018 academic year. When the obtained data were evaluated, it was found that majority of the teacher candidates had difficulty in expressing fully the concept of equation, and in perceiving the mathematical structure of the equations and in drawing the graphs of the equationsPeer Reviewe

Revised: 25.07.2007

In recent years, antiepileptic drug development has been one of the most prominent research areas. Although several new anticonvulsants are already in clinical use, some types of seizures are still not adequately treated with current therapy and have limitations intolerable side effects 1-3. I

Türkiye’ye tersine beyin göçü : nitel bir araştırma

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Göç, geçmişten günümüze tarihin tüm dönemlerinde önem arz eden bir olgudur. Göç hareketleri içerisinde beyin göçü de 1960'lardan itibaren özellikle küreselleşme süreciyle birlikte, ülkeler açısından üzerinde durulan bir konu olmaktadır. Dünyada beyin göçü hareketliliğinde; beyin göçü alma ve beyin göçü verme durumlarına göre ülkeler politikalar oluşturmaktadırlar. Beyin göçü alan ülkelerin başında; ABD, Kanada, Avustralya ve İngiltere gibi gelişmiş ülkeler gelmektedir. Bu ülkeler beyin göçünü çekmek için yüksek nitelikli bireylere imkanlar sunmaktadırlar. Beyin göçü veren ülkeler ise; beyin göçü alan bu gelişmiş ülkelerin beyin göçü çekme politikalarına karşı önlemler alma ihtiyacı duymaktadır. Özellikle gelişmekte olan ülkeler; gelişmiş ülkelere verdikleri kayıpları geri kazanmak için tersine beyin göçü politikaları uygulamaktadırlar. Beyin göçü veren ülkelerden Hindistan, Çin, Güney Kore, Tayland ve Tayvan gibi ülkeler, bu konudaki kayıplarını engellemek için tersine beyin göçü anlamında birçok politika ve projeye yer vermektedir. Beyin göçü türlerinden olan tersine beyin göçü de beyin göçü kaybı yaşayan gelişmekte olan ülkelerin gelişmiş ülkelerdeki yüksek nitelikli bireylerini ülkelerine çekme sürecidir. Bu çalışmada; tersine beyin göçü konusuna ilişkin olarak dünyadaki gelişmiş ülkelerin beyin göçü çekmesine ilişkin uyguladıkları politikalara karşılık, beyin göçü veren gelişmekte olan ülkelerin tersine beyin göçü politikalarına yer verilmiştir. Tersine beyin göçü konusu dünyadaki ülkelerin olduğu gibi Türkiye'nin de gündeminde olan bir konudur. Bununla ilgili olarak Türkiye'de; TÜBİTAK, ASELSAN, HAVELSAN ve birçok kurumun projeler ve politikalar geliştirdiği bilinmektedir. Bu çalışmada; beyin göçü ve tersine beyin göçü konusunda dünyadaki belirlenen ülkelerin ve Türkiye'nin mevcut politikaları değerlendirilmiştir. Araştırma olarak, Türkiye'ye döndükten sonra kamu kurumlarında, özel kurumlarda ve kamu özel iştiraklerinde çalışmaya başlayan yüksek nitelikli bireylerle yarı yapılandırılmış mülakatlar gerçekleştirilerek, nitel araştırma yöntemlerinden durum çalışması yapılmıştır. Yüksek nitelikli bireylerin tersine beyin göçü süreçlerine ilişkin verdikleri cevaplar, nitel analiz programı olan NVivo 12 Plus programı ile analiz edilmiştir. Elde edilen bulgularda; yüksek nitelikli bireylerin beyin göçü gerçekleştirmelerinde mesleki kazanımları için yurt dışında aldıkları eğitimin etkili olduğu, yurt dışında çalışma hayatı ve günlük hayata uyum sürecinde uyumu kolaylaştıran ve zorlaştıran faktörler olduğu, Türkiye'ye tersine beyin göçü gerçekleştirmelerinde de iş faktörlerinin, ülkelerine hizmet etme isteklerinin ve ailevi faktörlerin etkili olduğu, tersine beyin göçü sonrası Türkiye'de işe başlama süreci ile ilgili olarak; işe girmelerinde iş ilanları ve bursun etkili olduğu, çalıştıkları kurumlarda çalışma sebebi olarak da kendilerine sunulan çalışma imkanlarının etkili olduğu, Türkiye'ye tersine beyin göçünün gerçekleşmesi ve artması ile ilgili tavsiyelerinde çalışma ilişkilerinin düzenlenmesinin ve bilimsel desteklerin artmasının ön plana çıktığı anlaşılmıştır.Migration has always been an important phenomenon in history. Especially with the globalization period starting in 1960s, brain drain among migration movements has been an important subject for countries. In terms of global brain drain movement, countries form policies based on their brain drain receiving and giving conditions. Developed countries such as USA, Canada, Australia and England are the main brain drain recipient countries. These countries give opportunities to high qualified individuals to attract the reception of brain drain. Countries giving brain drain need to take precautions against the brain drain receiving policies of these developed countries. Especially developing countries apply reverse brain drain policies to recover their losses to developed countries. India, China, South Korea, Thailand and Taiwan among the countries giving brain drain apply many reverse brain drain policies and projects to prevent losses in this field. In developing countries giving brain drain, reverse brain drain as a type of brain drain is the phase of attracting high qualified individuals in developed countries to their own countries. Reverse brain drain policies of developing countries giving brain drain versus the policies applied by developed countries to attract brain drain were covered in this study. Just like other counties, reverse brain drain is a subject covered in Turkey's agenda. Many institutions such as TUBITAK (Scientific and Technological Research Council of Turkey), ASELSAN (Military Electronics Industries) and HAVELSAN (Air Electronic Industry and Trade) in Turkey are known to develop projects and policies on this subject. The present policies on brain drain and reverse brain drain in Turkey and countries chosen worldwide were evaluated in this study. As research, a case study among qualitative research methods was made through semi-structured interviews with high qualified individuals who started to work in public institutions, private firms and public-private partnerships after returning to Turkey. Responses provided by high-qualified individuals to questions on reverse brain drain phases were analyzed with NVivo 12 Plus program which is a qualitative analysis program. Based on acquired findings, it was understood that the occupational education taken abroad was effective for high-qualified individuals for making brain drain, there were factors making the adaptation to the daily or professional life abroad easier or more difficult, factors for brain drain from Turkey were professional factors, willingness to serve to their countries and familial factors and finally regarding the phase of starting to work in Turkey; job postings and scholarship were effective for finding jobs in Turkey, professional opportunities provided were effective as the cause for working in those institutions and organizing professional relations and increasing scientific support stood out in their suggestions for accomplishing and increasing reverse brain drain to Turkey. Differences were detected in the responses of high-qualified individuals depending on the institutions they work in Turkey after making reverse brain drain to Turkey

Üniversite Kütüphanelerinde Stratejik Planlama: Bir Araştırma

It is vital that business administrators should follow what is going on in external environment. Therefore, the external environment should be analized sistematically and frequently. In this study it was investigated that if the Turkish University Libraries, have the stratejic point of view or not and in their works, they do planning or not. Data was gathered through a questionnaire which was completed by academic libraries in Turkey. As a consequence, there is no strategic planning in the field of academic libraries in Turkey. İşletme yöneticilerinin dış çevrede, ne olup bittiğini takip etmeleri hayati bir önem taşımaktadır. Bunun için dış çevrenin sürekli olarak ve sistematik bir şekilde analiz edilmesi gereklidir. Bu çalışmada, Türkiye'deki üniversite kütüphanelerinin stratejik bakış açısına sahip olup olmadıkları ve planlamçı yapıp yapmadıkları incelenmiştir. Çalışmanın verileri üniversite kütüphanelerine uygulanan anketle sağlanmıştır. Sonuç olarak, ülkemizde üniversite kütüphanelerinde stratejik planlama yapılmadığı belirlenmiştir.

Teachers' and learners' perceptions about the effectiveness of grammar courses in The Foreign Languages Department of Anadolu University

Ankara : The Department of Teaching English as a Foreign Language, Bilkent University, 2001.Thesis (Master's) -- Bilkent University, 2001.Includes bibliographical references leaves 58-61.Grammar has always been one of the major concerns of researchers. Teacher and learner perceptions about grammar, on the contrary, have received less interest in the field. The purpose of this study was to investigate the teachers’ and the students’ perceptions about the effectiveness of the grammar courses in the Foreign Languages Department of Anadolu University. Twenty-two teachers who were teaching grammar at the time of the study and 141 students from beginner/elementary, lower intermediate/intermediate, and upper intermediate/ advanced levels participated in the study. Data was collected through two questionnaires which were parallel to each other. One of the questionnaires was for the teachers and the other was for the students. In data analysis, quantitative techniques were used. The results of the study revealed that both the teachers and the students wanted to have separate grammar courses. They were undecided about the effectiveness of the grammar courses. While the students believed that they were required to memorise the grammar rules, teachers disagreed with this statement. There were no differences among the levels in terms of their perceptions about the need and effectiveness of the grammar courses. However, some differences were observed in their perceptions about the way these courses were taught. For instance, upper intermediate and advanced level students were the ones who thought that their teachers encouraged them to discover grammar rules rather than explaining them. On the other hand, Lower Intermediate and Intermediate level students thought that their teachers did not encourage them to discover grammar rules, instead they explained them to the students. The findings of this study suggest that grammar courses should be maintained as part of the foreign language curriculum. However, since there are too many rules to cover in a short period of time, the study suggest that the load of the syllabus should be lightened so that students can find enough time to practice the grammar rules they are expected to learn.Çalış, GayeM.S

Performance modeling of communication networks offered with a mixture of persistent TCP and UDP flows

Ankara : The Department of Electrical and Electronics Engineering and the Graduate School of Engineering and Science of Bilkent University, 2013.Thesis (Master's) -- Bilkent University, 2013.Includes bibliographical references leaves 38-40.A damped fixed-point approximation is proposed to characterize the throughput of persistent TCP and UDP flows in a network of router links supporting per-class queuing and Deficit Round Robin (DRR) scheduling among classes. In particular, we study the case of two classes where one of the classes uses drop-tail queue management and is intended for UDP traffic. The other class targeting TCP traffic is assumed to use Active Queue Management (AQM). The effectiveness of the proposed analysis method in this scenario is validated by extensive NS3 simulations. Moreover, we study, using the proposed fixed-point algorithm, the potential gain of employing the many-to-one communications paradigm with respect to the conventional one-to-one communications in which a client downloads a specific content from one server only.Çalış, GökhanM.S