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GÜLLÜOĞLU, ARİF NİHAT

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GÜLLÜOĞLU

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ARİF NİHAT

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2010 - 20198
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End date: 2019 × Start date: 2010 ×

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Now showing 1 - 8 of 8
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    PublicationOpen Access
    The similar and dissimilar spot welding of 304 and 316l austenitic stainless steels
    (2017-11-01) ÇINAR, ÖZGÜR; ÇETİNER, BURCU NİLGÜN; GÜLLÜOĞLU, ARİF NİHAT; EKİCİ, BÜLENT; ÇINAR Ö., ÇETİNER B. N., TOPCU İ., GÜLLÜOĞLU A. N., EKİCİ B.
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    PublicationOpen Access
    Strategy Development Process in Higher Education: The Case of Marmara University
    (ELSEVIER SCIENCE BV, 2016-11) GÜLLÜOĞLU, ARİF NİHAT; Bakoglu, Refika; Oncer, Ayla Zehra; Yildiz, Muge Leyla; Gulluoglu, Arif Nihat; Ozsahin, M
    Strategic planning in higher education has become one of the most important factors of today's education system. State of the Republic of Turkey, which is aware of importance of this trend in the world, made the preparation and implementation of five-year strategic plans mandatory for higher education institutions. However, when examining the strategic plans made by universities in Turkey in general, it draws attention that strategy development techniques are not used in development processes. Strategies at different levels in universities are not taken in consideration, and strategies are not determined by high participation and not formed and implemented in a conscious way. Marmara University has developed a different and unique approach by considering these facts when doing researches to develop strategies to be effective in the next five-year period. In this notification, it is aimed to reveal strategical approach developed exclusive to universities in 2017-2021 strategic plan of Marmara University, and strategy development process model formed for the purpose of being internalized of strategy in institution. In this respect, in study; it is mentioned how participation of academic and administrative personnel is provided, in which way it is focused on creating value for all stakeholders, how internal and external environment analysis are made with which scientific research projects and how corporate learning is supported in every stage of the process. This paper tries to highlight a case from Marmara University's strategy development process indicating how strategic plan on the paper can be changed into internalized strategy creating change, momentum and dynamism trough the both implementation of a new approach to strategy and strategy development process. (C) 2016 The Authors. Published by Elsevier Ltd.
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    PublicationMetadata only
    Effect of surface geometry on low-velocity impact behavior of laminated aramid-reinforced polyester composite
    (SAGE PUBLICATIONS LTD, 2016) GÜLLÜOĞLU, ARİF NİHAT; Ayten, Ali Imran; Ekici, Bulent; Gulluoglu, Arif Nihat
    The aim of this study is to investigate the effect of surface geometry for low-velocity impact applications. To achieve this purpose, aramid fiber-reinforced laminated polyester composite with various geometries such as cylindrical, elliptical, and spherical were prepared, and low-velocity impact properties were investigated numerically and experimentally. All properties such as orientation, fiber volume fraction, matrix material, and average thickness are the same in all samples. Experimental low-velocity impact behaviors of structure were determined by drop weight tester at low velocity 2.012 m/s. Simulations were carried out by LS-Prepost 4.2 and LS-Dyna v971 software. By this way, results of impact tests were verified and modeled with finite element method. Results of the impact tests showed that the elliptical samples have the highest energy absorption capability due to effective stress transfer capacity. According to experimental results, maximum energy absorption rate difference is 17% between elliptical 10mm and cylindrical 5mm geometries.
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    PublicationOpen Access
    Investigation of wear behavior of Ti-6Al-4V/CNT composites reinforced with carbon nanotubes
    (GAZI UNIV, FAC ENGINEERING ARCHITECTURE, 2018-09-12) GÜLLÜOĞLU, ARİF NİHAT; Topcu, Ismail; Gulluoglu, Arif N.; Bilici, M. Kemal; Gulsoy, H. Ozkan
    In this study, the effects of different production conditions and different sintering conditions on microstructure, density and wear resistance of Multi-wall carbon nanotubes (CNTs) powders reinforced with Titanium (Ti-6Al-4V) powder by mechanical alloying were examined. The powders produced by mechanical alloying were compressed with a Cold Isostatic Press die under a pressure of 250 MPa in this molding machine to obtain cylindrical composite specimens. These raw specimens were extruded at 1275 degrees C for 60 minutes in a high purity argon atmosphere and high vacuum (1.2 10-5 mbar). The erosive wear behavior of the Ti-6Al-4V / CNTs metal matrix composite was studied using a pin-on-disc wear tester. The abrasion behavior of a Ti-6Al-4V / CNTs alloy after various heat treatments has been studied on abrasive wear. Under appropriate conditions it has been shown that reinforced CNTs can reduce the wear rate by more than two orders of magnitude. Various investigations have been carried out detailing the reinforcement rates of this improved wear performance. The friction and wear data show a clear surplus value added to the composite Ti-6Al-4V wear modes. As a result, in the experimental studies made, it is seen that the wear resistance increase according to the v/v % CNTs ratio which is directly supplemented to the volume. However, this properties had been decrease with the % 5 CNTs ratio.
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    Radiation induced modification of dielectric and structural properties of Cu/PMMA polymer composites
    (ELSEVIER SCIENCE BV, 2010) GÜLLÜOĞLU, ARİF NİHAT; Singh, Dolly; Singh, N. L.; Qureshi, Anjum; Kulriya, P.; Tripathi, Ambuj; Avasthi, D. K.; Gulluoglu, Arif N.
    In this study, composite films consisting of an insulating polymethyl methacrylate (PMMA) polymer matrix and metal powder (Cu) additive were prepared by solution costing method. These films were irradiated with 140 MeV silver ions at the fluences of 1 x 10(11) ions/cm(2) and 1 x 10(12) ions/cm2. The radiation induced changes in dielectric, structural and surface properties of PMMA/Cu composites were studied using impedance/gain phase-analyzer, X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). It was observed that the dielectric properties and ac electrical conductivity increased significantly with the concentration of dispersed metal powder (Cu) and also with the fluence. This reveals that ion beam irradiation creates free radicals, unsaturation etc. due to emission of hydrogen and/or other volatile gases, which makes the polymer more conductive. XRD analysis of the pristine and irradiated samples shows that the crystallinity improved upon irradiation at low fluence and deteriorated on further increase of the fluence, which could be attributed to cross linking of polymer chains at low fluence and degradation at higher fluence. High energy ion beam irradiation of semicrystalline polymer composite films changes its Tg behavior as observed from DSC analysis. This result is also corroborated with the results of XRD. The average surface roughness and topography of surfaces changed with the concentration of filler and also with the ion fluence as revealed from AFM/SEM analysis. (C) 2010 Elsevier B.V. All rights reserved.
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    IN THE JEWELRY, BRAZING AND LASER WELDING WITH PARAMETER OPTIMIZATION
    (POLSKA AKAD NAUK, POLISH ACAD SCIENCES, INST METALL & MATER SCI PAS, 2012) GÜLLÜOĞLU, ARİF NİHAT; Kallek, M.; Ataoglu, S.; Yagci, Y.; Bozkurt, H. N.; Gulluoglu, A. N.
    In this study, brazing and laser welding were experimentally compared for 9, 14 and 18 carat gold alloys in different color. The gold alloys were joined by laser welding and brazing and the microstructure, hardness, chemical composition, color of the weld joints were investigated. According to study, in laser welding, voltage, pulse duration, pulse diameter and frequency are the most important welding parameters that influence the quality of joints. Welded joints are characterized using three geometric parameters: penetration depth, width of heat affected zone and underfill defects. Finally, optimum laser welding parameters of different color of 9, 14 and 18 carat gold alloys were determined. It is observed that laser welding has numerous advantages compared to the other joining techniques used in the jewelry industry.
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    Electrical and Thermal Studies on the Polyvinylchloride/Carbon Black Composites Induced by High Energy Ion Beam
    (TAYLOR & FRANCIS LTD, 2010) GÜLLÜOĞLU, ARİF NİHAT; Singh, Dolly; Singh, N. L.; Qureshi, Anjum; Gavade, Chaitali; Avasthi, D. K.; Gulluoglu, Arif N.; Phase, D. M.
    Modification induced by energetic ion in polyvinylchloride (PVC)/carbon black (CB) composites was studied using impedance gain-phase analyzer, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Different concentrations of CB were dispersed in PVC films. These films were irradiated with 140 MeV Ag11+ ions at the fluences of 1 x 10(11) and 1 x 10(12)ions/cm(2). The ac electrical conductivity and dielectric response were studied as a function of filler, frequency and ion fluence. It was found that ac electrical conductivity increases with increasing the percentage of CB, frequency and ion fluence. The observed enhancement in ac electrical conductivity is attributed to the increase in the number of conduction paths created by the carbon black contents in the composites to give a higher electrical conductivity. An increase in dielectric constant was observed with the ion fluence and also with the carbon black content, which is attributed to the interfacial polarization of heterogeneous systems. Differential scanning calorimetry (DSC) analysis showed that the glass transition temperature (Tg) shifted towards lower temperature with increasing the ion fluence. It may be attributed to the scissioning of polymer chains and as a result increase of free radicals, unsaturation etc., which lead to the transformation of polymer into amorphous phase. Atomic force microscopy (AFM) studies revealed that the surface average roughness of the composites increases as filler concentration increases and decreases upon irradiation. SEM micrographs showed that carbon black particles organized into aggregates of micro spherical voids and decreased its size upon irradiation.
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    PublicationOpen Access
    Türkiye’de Metal Sektöründe Meydana Gelen İş Kazalarının Analizi
    (2019-03-31) GÜLLÜOĞLU, ARİF NİHAT; ESMA NUR GÜLLÜOĞLU;ARİF NİHAT GÜLLÜOĞLU
    Metal sektörü dünyada olduğu kadar ülkemizde de önemli bir sektör konumundadır. Üstün özellikleri nedeniyle, teknolojik gelişmelere bağlı olarak kullanım alanları hızla yaygınlaşan metaller endüstride geniş bir uygulama alanına sahiptir. Bütün sanayilerin lokomotifi niteliğinde olan metal sektörü, barındırdığı iş gücü ve ekonomik büyüklüğü bakımından Türkiye’nin en önemli sanayi kolu durumundadır. Günümüzde her alanda yaşanan hızlı değişim ile üretim ve rekabet artmakta, iş kazaları sonucu çalışanların sağlığına ve iş güvenliğine yönelik tehlikelerde çoğalmaktadır. Ülkemizde yaşanan iş kazaları sayısı bakımından metal sanayi iş kazası yoğunluğunun en yüksek olduğu sektördür. Bu çalışmada 2007-2016 yılları arasında Türkiye genelinde meydana gelen iş kazaları ile metal sektöründe yaşanan kazalara ait veriler incelenerek analiz edilmiştir. Ayrıca, Türkiye metal sektörü iş kazaları verileri Avrupa birliği üye ülkeleri ile karşılaştırılmıştır.