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Author

Mustafa Karhan

Bio: Mustafa Karhan is an academic researcher from Çankırı Karatekin University. The author has contributed to research in topics: Wetting & Electric field. The author has an hindex of 1, co-authored 6 publications receiving 3 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, a virtual laboratory to be used for the production of nanocomposite NdFeB magnets has been realized, where mathematical functions were created from the data related to Br (permanent magnetism), Hc (magnetic coercivity), BHmax, Tc (Curie temperature) and density obtained in the researches on different Nd FeB alloys in the laboratory.
Abstract: Magnets have an important place in electrical and electronic systems and applications nowadays. The developments in the field of magnets have also greatly expanded their usage areas. NdFeB magnets play active and important role in this development. In this study, design of virtual laboratory to be used for the production of nanocomposite NdFeB magnets has been realized. Maximum energy product (BHmax) is an important value for permanent magnets. The high BHmax value in small volume for the magnets is a desired criterion. In the study, mathematical functions were created from the data related to Br (permanent magnetism), Hc (magnetic coercivity), BHmax, Tc (Curie temperature) and density obtained in the researches on different NdFeB alloys in the laboratory. Additionally, Br functions were obtained by adding different additives (Co,Ti, Zr, Hf, V, Ta, Nb, Cr, W, Mo, Mn, Ni, Sb, Sn, Ge, Al, Bi) to the NdFeB magnets. A virtual laboratory is prepared with the created functions. The obtained results from the operation of the virtual laboratory system and the results obtained from Matlab Simulink and ANN (Artificial Neural Network) systems are compared. The designed and performed virtual laboratory system can be used both for industrial purposes and for educational purposes.

4 citations

Journal ArticleDOI
TL;DR: In this paper, a smart test platform was used to accelerate the initiation and growth of vented type water trees in laboratory environment, and the statistical values of these features were analyzed, and scatter plots of the standard deviations and mean values of the cepstral coefficients were plotted.
Abstract: In 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.

4 citations

Journal ArticleDOI
TL;DR: In this article, contact angle measurements of XLPE materials with different roughness values were carried out under the electric field, and the correlation between the electric fields, surface roughness, wettability, and contact angle was observed.
Abstract: XLPE material, which is widely used as a polymeric insulator in medium and high voltage applications, plays an active and important role in electricity transmission and distribution. The aging of XLPE materials due to various factors is inevitable. It is observed that fault and troubleshooting increase with the aging of materials. Wettability behavior is one of the fundamental surface properties of materials. Surface properties also play an important role in the determination and estimation of the service life of the materials. By performing contact angle measurements for XLPE material surfaces, determinations and evaluations about the wettability behavior (hydrophobicity and hydrophilicity) of the materials can be made. In this study, contact angle measurements of XLPE materials with different roughness values were carried out under the electric field. With the help of the experimental setup designed and implemented, XLPE samples were placed between the aluminum plane electrodes and exposed to the electric field. 10 kV HVDC high-voltage generator was used when performing the measurements. 1.8 M (molarity) saltwater in the volume of 20 µl was dropped on the XLPE sample surface with a syringe and the droplet snapshots were taken with a digital microscope for contact angle measurement under the electric field. The acquired images were processed using basic image processing techniques with the help of a GUI developed on the MATLAB software platform. Contact angle values were obtained for 50 XLPE-A (Ra = 0.469 µm) and 50 XLPE-B (Ra = 5.456 µm) sample surfaces. Contact angles obtained from rough XLPE surfaces under the electric field allow for evaluation of the service life of XLPE materials. While determining and evaluating the wettability behavior of XLPE materials, an approach based on the contact angle is presented. As a result, the correlation between the electric field, surface roughness, wettability, and contact angle was observed. When the results were evaluated, it was observed that the contact angle values close to the hydrophobic surface value approached the hydrophilic values as a result of the increase in surface roughness and/or exposure to the electric field.

1 citations

Journal ArticleDOI
TL;DR: In this paper, the wettability characteristics of poly(methyl methacrylate) (PMMA) dielectric material which is used in high voltage applications and outdoor electrical applications in the presence and absence of the electric field was investigated.
Abstract: In this study, the wettability characteristics of Poly (methyl methacrylate) (PMMA) dielectric material which is used in high voltage applications and outdoor electrical applications in the presence and absence of the electric field was investigated. Saltwater droplets with a conductivity of 135.9 mS/cm were dropped onto the surface of a 5-mm thick PMMA dielectric material placed between two aluminum plane electrodes with a distance of 10 mm between them, and then 10 kV was applied between two aluminum electrodes. In the developed and implemented experimental platform, contact angle measurements were carried out using image processing techniques to interpret the wettability behavior of dielectric materials in the absence of the electric field and under HVDC. Wettability is one of the concepts used in the analysis of surface properties of materials and encountered in many engineering and science fields. Within the scope of this study, it is aimed to observe and analyze the correlation between the wettability characteristics, droplet shape, and contact angle under an electric field which has an important place under the topic of materials in science and engineering. Experimental results show that the electric field and the droplet liquid properties affect the contact angle and droplet shape. It was observed that the contact angle values decreased in the presence of the electric field and the apex of the droplet shape becomes more acute under the electric field.
Journal ArticleDOI
TL;DR: In this article, Gunumuzde NdFeB miknatislardaki gelismeler, bircok teknoloji alaninda vazgecilmez unsur haline gelmelerine sebep olmuslardir, egitim ve uretim teknikleri uzerinde buyuk bir etkiye neden olmustur.
Abstract: Bilgi ve iletisim teknolojisi alanindaki son gelismeler, egitim ve uretim teknikleri uzerinde buyuk bir etkiye neden olmustur. Sanal enstruman kavrami, olcum ve uretim sistemleri tasarimi alaninda yeni tekniklerin uygulanmasina yol acmistir. Sanal enstrumanlar, gercek laboratuvarlarin ana parcasi olan pahali ve karmasik gercek enstrumanlarin yerini almaya baslamistir. Boylece laboratuvarlarin tasarlanmasi, gerceklestirilmesi ve modernlestirilme sureci kolaylasmistir. Gunumuzde NdFeB miknatislardaki gelismeler, bircok teknoloji alaninda vazgecilmez unsur haline gelmelerine sebep olmuslardir. NdFeB miknatislar, maksimum enerji carpimi BH max sayesinde hibrit elektrikli araclarin motorlarinda yaygin olarak kullanilmaya baslamistir. Ayrica manyetik rezonans goruntuleme, elektrikli motorlar, cesitli jeneratorler gibi uygulamalarda, buyuk olcekli veya kucuk olcekli ruzgar enerjisi jeneratorlerinde kullanimlari onemli olcude artmistir. Bu calismada NdFeB miknatislarin uretimi oncesinde AR-GE calismalarinda ve uretimde kullanilabilecek sanal bir laboratuvar platformu gerceklestirilmistir. Gelistirilen sanal platform masaustu uygulamasi olarak tasarlanip calistirilmistir. Ileriki calismalarda acik kaynak donanimlar kullanilarak web tabanli uygulamalar gelistirilecektir. Calismada, gercek laboratuvarda farkli NdFeB alasimlari uzerine yapilan arastirmalarda elde edilen B r (kalici miknatisiyet), H c (manyetik koersivite), BH max (maksimum enerji carpimi) ve Curie sicakligi ile ilgili verilerden matematiksel fonksiyonlar elde edilmistir. Elde edilen fonksiyonlar ile sanal laboratuvar platformu hazirlanmistir. Olusturulan laboratuvar sistemi cok amacli olarak endustride kullanilabilecegi gibi egitim amacli da kullanilabilir. Miknatis tasarimindaki AR-GE calismalari sirasinda maliyet ve zaman tasarrufu saglamasi ve yeni miknatis calismalarinin onunun acilmasi hedeflenmektedir.

Cited by
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Journal ArticleDOI
TL;DR: In this paper, the dynamic failure process and characteristics of sintered NdFeB under high-speed impact were explored, which provided an experimental basis for the following theoretical research.

15 citations

Journal ArticleDOI
TL;DR: In this article , a magnetically targeted, water-triggered, self-healing microcapsule (MTWTSH-MC) was proposed to solve the problem of residual water preventing the healing agent from filling the water tree branch channel.
Abstract: Repairing the micro-scale damage of insulating materials under a strong electric field has long been a highly desired but challenging task. Among all kinds of damage, water tree damage in the insulating materials of electrical equipment and electronic devices working in humid environments has long been considered irreparable. The main challenge is that residual water prevents the healing agent from filling the water tree branch channel. To solve this problem, this work reports a magnetically targeted, water-triggered, self-healing microcapsule (MTWTSH-MC) that makes a breakthrough against water tree damage based on microfluidic techniques. Targeted microcapsules driven by a directional magnetic field are concentrated to the vulnerable area of the insulating materials, exerting very limited effects on the dielectric. When damage breaks the microcapsules, the healing agent releases and quickly fills the damage channel and then reacts with water in the air or in the branch channel of the water tree, achieving solidification of the healing agent and self-healing of the damage channels. In this way, we can realize self-perception, self-triggering, and self-healing for both mechanical damage and water tree damage in insulation materials without any external stimulation.

3 citations

Journal ArticleDOI
TL;DR: In this paper , a lightweight method has been proposed for the early detection of faults in UAV motors using Mel-frequency Cepstral Coefficients (MFCC) method.

2 citations