The relations between null geodesic curves and timelike ruled surfaces in dual Lorentzian space $\mathbb{D}_{1}^{3}$

Yasin \"{U}nl\"{u}t\"{u}rk,S\"{u}ha Y\i lmaz,Cumali Ekici 호남수학회 2019 호남수학학술지 Vol.41 No.1

In this work, we study the conditions between null geodesic curves and timelike ruled surfaces in dual Lorentzian space. For this study, we establish a system of differential equations characterizing timelike ruled surfaces in dual Lorentzian space by using the invariant quantities of null geodesic curves on the given ruled surfaces. We obtain the solutions of these systems for special cases. Regarding to these special solutions, we give some results of the relations between null geodesic curves and timelike ruled surfaces in dual Lorentzian space.

A new description of spherical images associated with minimal curves in the complex space $\mathbb{C}^{4}$

Yasin Unluturk,Suha Yilmaz 호남수학회 2022 호남수학학술지 Vol.44 No.1

In this study, we obtain the spherical images of minimal curves in the complex space in $\mathbb{C}^{4}$ which are obtained by translating Cartan frame vector fields to the centre of hypersphere, and present their properties such as becoming isotropic cubic, pseudo helix, and spherical involutes. Also, we examine minimal curves which are characterized by a system of differential equations.

Design of novel electrode for capacitive deionization using electrospun composite titania/zirconia nanofibers doped-activated carbon

Yasin, Ahmed S.,Mohamed, Ibrahim M.A.,Park, Chan Hee,Kim, Cheol Sang Elsevier 2018 Materials letters Vol.213 No.-

<P><B>Abstract</B></P> <P>Well-dispersed TiO<SUB>2</SUB>/ZrO<SUB>2</SUB> nanofibers-doped activated carbon (AC/TiZr) were successfully synthesized as an electrode for the capacitive deionization (CDI) technique via electrospinning that was followed by a hydrothermal treatment. SEM, TEM, XRD, XPS and EDX measurements were employed to characterize the morphology, crystal structure and chemistry composition of the as-synthesized material. The electrochemical performance of the AC/TiZr nanocomposite modified electrode was measured using systematic cyclic voltammetry (CV) experiments. The highest specific capacitance for the AC/TiZr-based electrode is 251.3 Fg/g, which is higher than those of the AC (207.4 Fg/g) and TiO<SUB>2</SUB>/ZrO<SUB>2</SUB> NFs (0.4 Fg/g)-based electrodes, and the interior resistance was also reduced. A desalination performance enhancement was obtained in the case of the AC/TiZr and the electrosorptive is 2.96 mg g<SUP>−1</SUP>. The implementation of the AC/TiZr nanocomposite provided a high potential for improving the efficiency of CDI.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Effective TiO<SUB>2</SUB>/ZrO<SUB>2</SUB> NFs incorporated AC are introduced for CDI. </LI> <LI> Improvement in wettability (16.9°) is due to modifying the carbon-based electrode. </LI> <LI> Low inner resistance and high specific capacitance are observed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

요르단 아랍어의 아람어 차용어휘에 관한 고찰

Yasin, Raslan Bani 한국외국어대학교 1990 한국외국어대학교 논문집 Vol.23 No.1

A NEW MODELLING OF TIMELIKE Q-HELICES

( Yasin Ünlütürk ),( Cumali Ekici ),( Doǧan Ünal ) 호남수학회 2023 호남수학학술지 Vol.45 No.2

In this study, we mean that timelike q-helices are curves whose q-frame fields make a constant angle with a non-zero fixed axis. We present the necessary and sufficient conditions for timelike curves via the q-frame to be q-helices in Lorentz-Minkowski 3-space. Then we find some results of the relations between q-helices and Darboux q-helices. Furthermore, we portray Darboux q-helices as special curves whose Darboux vector makes a constant angle with a non-zero fixed axis by choosing the curve as one of the types of q-helices, and also the general case.

Theoretical insight into the structure-property relationship of mixed transition metal oxides nanofibers doped in activated carbon and 3D graphene for capacitive deionization

Yasin, Ahmed S.,Mohamed, Ahmed Yousef,Mohamed, Ibrahim M.A.,Cho, Deok-Yong,Park, Chan Hee,Kim, Cheol Sang Elsevier 2019 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.371 No.-

<P><B>Abstract</B></P> <P>Over the last two decades, the capacitive deionization (CDI) technique has been developed into a high performance, low-cost, and environmental-friendly desalination technology. The development of novel advanced nanostructures via the hybridization of diverse carbon materials to improve the performance of CDI technology has attracted considerable attention. In this study, the combination of graphene hydrogel and ZrO<SUB>2</SUB>-doped TiO<SUB>2</SUB> nanofibers as efficient dopants into activated carbon (AC), has been achieved through a simple electrospinning technique followed by a post annealing process. The strong interactions between the graphene hydrogel, nanofibers and AC were found to enhance the wettability as well as the electrical conductivity of the AC. The morphology and electrochemical performance of the as-synthesized composite were characterized by field-emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). What’s more, the X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and synchrotron X-ray absorption structures (XAS) are performed to investigate the atomic and electronic structure of titania and zirconia in order to understand their phase stability. We observed the appearance of anatase structure of titania and cubic structure of zirconia after doping the AC and graphene hydrogel with the nanofibers. The water contact angle of the composite was examined and found to be less than 3°. The introduced nanocomposite showed high electrosorption capacity of 9.34 mg g<SUP>−1</SUP> at the initial solution conductivity of ∼100 μS cm<SUP>−1</SUP>, which is much higher compared to the other surveyed materials; these results should be attributed to its significant hydrophilicity, high specific capacitance, and reduced charge transfer resistance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Unique three-dimensional graphene/mixed transition metal oxides modified activated carbon was prepared and characterized. </LI> <LI> The nanocomposite electrode shows low charge transfer resistance and high specific capacitance. </LI> <LI> Analysis of synchrotron-based hard X-ray absorption spectroscopy. </LI> <LI> The fabricated nanocomposite exhibits a high electrosorption capacity of 9.34 mg g<SUP>−1</SUP>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Enhanced desalination performance of capacitive deionization using zirconium oxide nanoparticles-doped graphene oxide as a novel and effective electrode

Yasin, A.S.,Mohamed, H.O.,Mohamed, I.M.A.,Mousa, H.M.,Barakat, N.A.M. Elsevier Science B.V 2016 Separation and purification technology Vol.171 No.-

Due to its eco-friendly and low energy technique for removing salt ions from saline water, capacitive deionization (CDI) is highly recommended as a desalination process. Based on its good features, large surface area and good electric conductivity, graphene oxide is a promising electrode in the CDI technology if the specific capacitance could be enhanced. In this study, to improve the electrochemical performances, novel ZrO<SUB>2</SUB> nanoparticles-incorporated graphene oxide nanosheets with different concentrations were successfully synthesized by hydrothermal treatment, their electrosorption characteristics in CDI unit were examined. The morphology, structure and electrochemical performance of the fabricated materials were investigated by scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), cyclic voltammetry and electrochemical impedance spectroscopy. The capacitive and electrosorption performances in NaCl solution were studied. Moreover, the role of ZrO<SUB>2</SUB> loading was investigated. The introduced ZrO<SUB>2</SUB>-doped graphene oxide showed a distinct improvement in the electrosorption capacity and revealed higher specific capacitance compared to the pristine graphene oxide. The obtained results indicated that the synthesized ZrO<SUB>2</SUB>-doped graphene oxide nanocomposite having 10wt.% ZrO<SUB>2</SUB> displayed a significant increase in the specific capacitance as the corresponding value (452.06F/g) was nine folds more than that of the pristine GO at 10mV/s. Moreover, the same electrode exhibits great cycling stability, excellent salt removal efficiency (93.03%), and distinct electrosorptive capacity (4.55mg/g). Overall, the proposed GO/ZrO<SUB>2</SUB> nanoparticle composite electrode is appropriate for utilizing as optimum electrodes for the CDI technique.

Microstructure and Mechanical Properties of Severely Deformed Eutectic Al–Si–Cu–Mn Alloy

Yasin Alemdağ,Sadun Karabiyik,Gençağa Pürçek 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.4

In this study, the microstructure and mechanical properties of severely deformed Al–12Si–3Cu–0.5Mn alloy were systematicallyinvestigated. The alloy produced by permanent mold casting was homogenized and processed with multi-directionforging (MDF) up to four cycles at 200 °C. MDF gave rise to fragmentation of hard particles, formation of dispersoids, andfine grains with high angle grain boundaries. The grain size of the alloy after one-cycle MDF decreased from 27.30 μm tosub-micron levels of about 0.5 μm. After one-cycle MDF, the formed microstructure consisted of ultrafine grains (UFG) withand without intense dislocations. Lattice microstrains and dislocation densities of the alloy decreased with increasing forgingcycles. In general, hardness, yield and tensile strength, elongation and impact toughness of the alloy increased after MDF. The highest hardness, yield and tensile strength of the alloy were obtained after the two-cycle MDF, while the four-cycleMDF produced the highest elongation and impact toughness values. Fracture surface of the tensile tested alloy before MDFconsisted of large cleavage planes and hills. However, narrow cleavage planes and plenty of dimples occurred on the tensilefracture surface of the alloy after MDF. These findings were elucidated according to microstructural alterations as a resultof fragmentation of hard particles, formation of dispersoids and fine grains, annihilation of dislocations and grain growth.

Numerical evaluation of effects of shear span, stirrup spacing and angle of stirrup on reinforced concrete beam behaviour

Yasin Onuralp Özkılıç,Ceyhun Aksoylu,Musa Hakan Arslan 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.79 No.3

Shear and bending strength of reinforced concrete beams depend on many parameters. It is extremely important to take the necessary precautions in terms of shear in order for the beams to reach their bending capacity. For this reason, it is necessary to determine the effective parameters especially on shear capacity in beams. However, the actual capacity calculation is quite difficult according to regulations that are very conservative in terms of design. Therefore, many experimental studies have been conducted on the shear capacity of the beams. However, this situation is not meaningful in terms of both time and cost, since many experiments will be required to interpret the beam shear behavior, which depends on many parameters. For this reason, the use of advanced software whose verification is performed according to experimental data has become widespread. In this study, a numerical study was carried out on 36 different beam models using the ABAQUS finite element program to examine the effect of the shear span/effective depth (av/d) ratio, stirrup spacing (sw) and the angle of stirrup (α). The results showed that as the av/d increase, the behavior of a shear deficient beam tends to typical bending behavior. Although the effect of stirrup angle on shear capacity is quite high, stirrup angles of 30° and 60° give very similar results. The effect of stirrup spacing is quite limited at relatively high av/d. Stirrups with 90° do not contribute to ductility in beams with high av/d.

Effect of polyfunctional monomers on properties of radiation crosslinked EPDM/waste tire dust blend

Yasin, T.,Khan, S.,Nho, Y.C.,Ahmad, R. Pergamon 2012 Radiation physics and chemistry Vol.81 No.4

In this study, waste tire dust is recycled as filler and blended with ethylene-propylene diene monomer (EPDM) rubber. Three different polyfuntional monomers (PFMs) are incorporated into the standard formulation and irradiated under electron beam at different doses up to maximum of 100kGy. The combined effects of PFMs and absorbed dose on the physical properties of EPDM/WTD blend are measured and compared with sulfur crosslinked formulation. Thermogravimetric analysis showed that radiation developed better crosslinked network with higher thermal stability than sulfur crosslinked structure. The physical properties of radiation crosslinked blend are similar to the sulfur crosslinked blend. The absence of toxic chemicals/additives in radiation crosslinked blends made them an ideal candidate for many applications such as roof sealing sheets, water retention pond, playground mat, sealing profile for windows etc.