Yazar "Uğur, Mukden" seçeneğine göre listele
Listeleniyor 1 - 8 / 8
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe A new approach to the analysis of water treeing using feature extraction of vented type water tree images(Springer, 2021) Karhan, Mustafa; Çakır, Musa Faruk; Uğur, MukdenIn this study, vented type water trees were initiated and grown in laboratory environment. A smart test platform was used to accelerate the initiation and growth of vented type water trees. 6 kV/4 kHz voltage was applied to the specimens to initiate and grow water trees. Mel-frequency cepstral coefficients of the vented type water tree images are obtained after 2 h and 10 h of aging respectively. The insignificant regions in the vented type water tree images were removed by using morphological filtering method before MFCC feature extraction. Finally, the statistical values of these features were analyzed. Scatter plots of the standard deviations and mean values of the cepstral coefficients were plotted. As expected, it has been observed that the points in the scatter plot are clustered in a certain area. MFCC is a popular and frequently used feature extraction method in speech recognition, however there are some studies which employs MFCC as a successful feature extraction method in image processing applications. This study provides a new approach to the analysis of vented water treeing using image processing techniques. The other new approach is using MFCC as a feature extraction method in microscopic water tree images.Öğe Analysis of electric field and potential distribution of experimental setup for initiating and growing vented type water trees using finite element method(Editura Bibliotheca-Bibliotheca Publ House, 2020) Karhan, Mustafa; Çakır, Musa Faruk; Uğur, MukdenWater treeing phenomenon has an important and effective role in the service life of polymeric insulators used in the transmission and distribution of electricity. Water trees can be described as permanently localized degradations or damages that can occur in the presence of electric field and humidity. XLPE is widely used as a polymeric insulator material in medium and high voltage cable applications. An experimental setup was prepared to initiate and grow water trees artificially in a laboratory environment and the tests were performed in accordance with the actual values. The electrical and dielectric values of the test material were used for a detailed analysis with high accuracy. The magnitude of the electric field, which was defined by varying the distance between the water needles formed in the XLPE material and the aluminium plate electrode, has been analyzed for various conditions. After laboratory experiments, electric field and potential distribution were simulated and analyzed by FEM (Finite Element Method) using FEMM (Finite Element Method Magnetics) software package. Experiments revealed clearly, that even small changes in the shape of water needle can dramatically affect the electric field and hence the lifetime of the insulator. By using FEMM, both of these parameters (electric field and potential distribution) can be calculated rapidly with high accuracy. HVDC power cables play a significant role in electric power transmission, hence by using the previously described experimental setup, electric field and potential distribution were simulated and analyzed under DC voltage.Öğe Electromagnetic investigation of neuron growth by using pulsed electromagnetic field stimulation(Elsevier, 2023) Kara, S.; Uzunoğlu, C. P.; İşçi, E. T.; Atalar, F.; Uğur, MukdenElectromagnetic field (EMF) applications for humans have been widely used for medical therapy for a long time. Various nerve diseases such as complex regional pain syndrome, cerebral palsy and spinal cord injuries may occur as a result of damage on the nerve cells. In addition, EMF applications are taken into consideration in terms of tissue regeneration. The use of electricity for nerve regeneration is applied internally or externally. The use of direct current (DC) electric fields to stimulate axon elongation and nerve regeneration in nerve cells has been applied in various studies. In our study, electromagnetic field was used for the controlled and directional growth of Dorsal Root Ganglia (DRG) nerve cells. An amplifier circuit, which can produce amplified signals to generate proposed pulsed electromagnetic fields (PEMF) is designed. The electromagnetic field is produced on FR-4 copper plate, which highlights electrical field unlike previous studies, since there is no circular coil structure preferred. The elongation of nerve cells is planned to be in one direction, hence the signal to be applied is produced as a novel asymmetrical waveform (sawtooth) in addition to triangular and square waveforms which were previously preferred in recent studies. By the aid of proposed novel construction and produced signal waveform, PEMF system can be applied for nerve diseases effectively. The morphological nerve cell elongation results and PEMF results have been investigated and the effectiveness of the proposed system is verified.Öğe Investigation of the effect of layered structure on partial discharges in transformer pressboard insulator(Springer, 2023) Uğur, Mukden; Atalar, Fatih; Önhon, N.ÖzbenThe dielectric performance of pressboards impregnated with mineral oil is one of the key points in regard to the quality of the transformer’s working life. Partial discharges (PDs) occurring in the pressboard can cause some insulation defects which might be one of the major reasons for an electrical breakdown. Detection of the PDs in pressboards gives a chance to understand the dielectric behavior of the insulators, hence major defects can be prevented just in early stage. The main point of the study is to investigate the differences in dielectric performance of layered and non-layered pressboards in the presence of PDs. For this purpose, the PD behavior of a layered pressboard with three layers (each with a thickness of 0.5 mm) and of a non-layered (solid) pressboard (with a thickness of 1.5 mm) is examined for two different high voltage levels (20 and 30 kV). To detect the PDs, Hall Effect Sensors are employed, considering that PDs cause fluctuations in the magnetic field. To analyze the magnetic field measurements from a statistical point of view, the Kaplan–Meier method and the Weibull analysis are used.Öğe Investigation of the effects of additives on the electrical and magnetic properties of polyester resin(Istanbul University Cerrahpaşa, 2022) Nişancı, Salih; İpekoglu, Mehmet; Nişancı, Muhammet Hilmi; Karhan, Mustafa; Uğur, MukdenPolymers are widely used as insulation materials in the electrical industry because their existing electrical and mechanical properties can be altered by adding different types of additives. Successful prediction of the service life of the insulators used in the electrical industry is important for the reliability of the system. For this purpose, insulating materials are subjected to tests according to various standards. In this study, unlike the literature, a polymeric insulator was produced by adding 3 wt.% zinc oxide (ZnO), magnetite (Fe 3O 4), and nickel (Ni) into the polyester. The produced samples were subjected to the inclined plane test in accordance with ASTM (American Society for Testing and Materials) D-2303 standards. In order to analyze the electric and magnetic field distributions formed on the samples during the inclined plane test, first, the current flowing on the samples during the test was measured. Following this, analyses were carried out by creating a simulation model of the samples. Studies found in the literature mainly focus on two-dimensional investigation of the electrical field distribution. This study concentrates on the three-dimensional examination of the electrical field also considering the magnetic field distribution. Results of this study showed that prior numerical analysis gives insight into information about the real-life behavior of the samples.Öğe Ion-imprinted polymer-on-a-sensor for copper detection(MDPI-Multidisciplinary Digital Publishing Institute, 2022) Gerdan, Zeynep; Saylan, Yeşeren; Uğur, Mukden; Denizli, AdilThe accumulation of metal ions in the body is caused by human activities and industrial uses. Among these metal ions, copper is the third most abundant ion found in the human body and is indispensable for health because it works as a catalyst in the iron absorption processes. However, high doses of copper ions have been reported to generate various diseases. Different types of sensors are used to detect metal ions for several applications. To design selective and specific recognition sites on the sensor surfaces, molecular imprinting is one of the most used alteration methods to detect targets by mimicking natural recognition molecules. In this study, an ion-imprinted polymer-integrated plasmonic sensor was prepared to selectively detect copper (Cu(II)) ions in real-time. Following different characterization experiments, the Cu(II)-imprinted plasmonic sensor was employed for kinetic, selectivity, and reusability studies. According to the results, it was observed that this sensor can measure with 96% accuracy in the Cu(II) concentration range of 0.04-5 mu M in buffer solution. The limit of detection and limit of quantification values were computed as 0.027 mu M and 0.089 mu M. The results also showed that this plasmonic sensor works successfully not only in a buffer solution but also in complex media such as plasma and urine.Öğe Manyetik Alan Etkisi Altinda Polimerik İzolatör Performans Testi(Bilecik Şeyh Edebali Üniversitesi, 2019) Atalar, Fatih; Türkay, Doğan; Yıldırımçakar, Arif; Yılmaz, Aysel Ersoy; Uğur, MukdenÇevresel ve elektriksel zorlayıcı etkiler enerji iletim dağıtım hattında yaygın olarak kullanılan silikon izolatörlerin yaşlanmasına sebep olurlar ve dielektrik performanslarını azaltırlar. Mekanik olarak taşıma kolaylığı, esnekliği ve hafifliği ile öne çıkan silikon izolatörler aynı zamanda yüksek elektrik direncine de sahiptir. Bu yalıtkanların yapısındaki herhangi bir bozulma, elektrik kesintilerine neden olarak ciddi finansal kayıplara yol açabilir. Enerji iletim-dağıtım hattı boyunca izolatörlerde, tellerden geçen akımın ürettiği manyetik alanın etkisi vardır. Bu alan, yalıtkan üzerindeki çalışma performansını değiştirecek bir etkiye neden olabilir. Bu çalışmada, silikon izolatörlerin çalışma performansını etkileyen AC manyetik alan, eğik düzlem testinde IEC 60587 ve ASTM 2303 standartlarına göre incelenmiştir. Ek olarak, üretilen bir elektrik alan ve kapasitif etki test edilmiştir. Numunelerin test süreleri, yalıtkan yüzeyinde üst elektrottan toprak elektroduna akan kaçak akım ve yüzey koşulları incelenmiş ve sonuçlar karşılaştırılmıştır.Öğe Partial discharge detection in pressboards immersed in mineral insulation oil with quantum well hall effect magnetic field sensors(IEEE, 2022) Atalar, Fatih; Dokur, Emrah; Balaban, Ertan; Missous, Mohamed; Uğur, MukdenInsulation degradation may cause inefficient and faulty operation of transformers. The insulation failures in transformers mostly start with a Partial Discharge (PD) event. For both operational and cost reasons to ensure the best performance and functionality of transformers, early detection of PD events is of great importance. In this paper presents a novel PD detection technique by using a highly sensitive Quantum Well Hall Effect (QWHE) magnetic field sensor and compares the findings with an off-the-shelf silicon magnetic field transducer. The investigation of the QWHE for high voltage engineering problem such as PD detection is given first time in this paper. The aim of the study is to detect PD activity in pressboards immersed in mineral insulation oil experimentally using a new QWHE sensor. The measured experimental data from both sensors are decomposed by Empirical Mode Decomposition (EMD) and Wavelet Decomposition (WD) methods, and PD signals are analyzed comparatively. The results show that QWHE sensors provide more accurate and noise-free measurements allowing early and more accurate PD detections.
