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.

Gender Differences in Responses towards Anti-Smoking Messages and Policy Implementation among Future Doctors in Malaysia

Yasin, Siti Munira,Ismail, Nurhuda,Noor, Norizal Mohd,Azman, Mohd Shafiq Mohd,Taib, Hanisah,Jusop, Junainah Mat,Salaudin, Nur Atirah Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.1

Background: Medical students' views may provide some direction for future policy considerations. Aim: The aim of this study was to assess gender differences in future doctors' receptiveness to currently implemented anti-smoking messages and the effectiveness of those messages. Materials and Methods: We administered a questionnaire to all students at a medical university in Malaysia, asking how frequently they noted anti-smoking policies, anti-smoking campaigns, and anti-smoking messages in schools. In addition, the questionnaire investigated most effective methods to convey these messages. Results: A total of 522 (59.7%) students responded. Students were least likely to approve of total bans on cigarettes and increasing the price of cigarettes, and most likely to approve of bans on use of cigarettes in public places and sales to individuals less than 16 years old. Approval of total bans on cigarettes was more common in female students than in males OR=0.39 (95%CI: 0.18-0.86). Furthermore, compared to the female students, the male students thought that printed media; OR=2.32 (95%CI: 1.31-4.10), radio; OR=1.93 (95%CI: 1.15-3.22) and the internet; OR=1.96 (95%CI: 1.15-3.33) were very effective at delivering anti-smoking messages. Conclusions: Gender differences existed in the future doctors' perception of the effectiveness of anti-smoking initiatives. Taking this gender difference into account may increase the receipt of anti-smoking messages in adolescents.

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.

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.

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>

Optimized stiffener detailing for shear links in eccentrically braced frames

Yasin O. Özkılıç 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.39 No.1

Eccentrically braced frames (EBFs) are utilized as a lateral resisting system in high seismic zones. Links are the primary source of energy dissipation and they are exposed to high deformation, which may lead to buckling. Web stiffeners were introduced to prevent buckling of shear link. AISC 341 provides the required vertical stiffeners for a shear link. In this study, different stiffener configurations were examined. The main objective is to improve the behavior of short links using different stiffener configurations. Pursuant to this goal, a comprehensive numerical study is conducted using ABAQUS. Shear links with different stiffener configurations were subjected to cyclic loading using loading protocol mandated by AISC 341. The results are compared in terms of energy dissipation and shear capacities and rupture index. The proposed stiffener configurations were further verified with different link length ratios, I-shapes and thickness of stiffener. Based on the results, the stiffener configuration with two vertical and two diagonal stiffeners perpendicular to each other is recommended. The proposed stiffener configuration can increase the shear capacity, energy dissipation capacity and the ratio of energy/weight up to 27%, 38% and 30%, respectively. Detailing of the proposed stiffener configuration is presented.

The Determination of Elementary School Students` Successes in Choosing an Operation and the Strategies They Used While Solving Real-World Problems

Yasin Soylu 韓國數學敎育學會 2007 수학교육연구 Vol.11 No.4

Chemical, Antioxidant and Sensory Profiling of Vitamin K-rich Dietary Sources

Yasin, Muhammad,Butt, Masood Sadiq,Yasmin, Adeela,Bashir, Shahid The Korean Society for Applied Biological Chemistr 2014 Applied Biological Chemistry (Appl Biol Chem) Vol.57 No.2

In present research, vitamin K-rich dietary food products were prepared from spinach & soybean and evaluated for nutritional factors, phylloquinone and menaquinone-7 (MK-7) contents and sensory attributes. For the purpose, two spinach-based products (fresh cooked spinach (FCS), reconstituted spinach (RS), and fermented soybean (natto A; NA and Natto B; NB) were formulated. Nutritional composition indicated that natto were rich in protein and fat compared to spinach-based products. They also contained appreciable amount of mineral i.e. potassium, magnesium, calcium zinc, sodium cupper, and iron. High performance liquid chromatography revealed that FCS contained $368.81{\pm}13.96{\mu}g/100g$ of phylloquinone followed by $270.07{\pm}9.45{\mu}g/100g$ in RS, whereas minimum value $26.90{\pm}0.94{\mu}g/100g$ was observed in NA. However, maximum MK-7 concentration was recorded in NA at $803.82{\pm}21.14{\mu}g/100g$ trailed by NB $681.35{\pm}16.85{\mu}g/100g$. On the contrary, MK-7 was not detected in the spinach-based products. Antioxidant indices of products indicated that spinach-based products contained higher amount of the total phenolic content, DPPH free radical-scavenging activity, ferric reducing antioxidant power (FRAP), and antioxidant activity compared to natto. Sensory response of the products showed that spinach-based products attained higher scores than those of natto A and B. Conclusively, FCS and NA contained sufficient amount of phylloquinone and MK-7 along with antioxidant activity and has higher potential to modulate the coagulation and bone related abnormalities.

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.

The effects of stiffener configuration on stiffened T-stubs

Yasin Onuralp Özkılıç 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.44 No.4

The stiffeners, also known as ribs, are utilized to increase the resistance of T-stubs. The author’s previous studies showed that stiffeners can increase plastic capacity by an average of 1.71 times. A combined experimental and numerical study was undertaken to examine the effects of the stiffener configuration on the behavior of T-stubs. A total of 20 stiffened T-stubs where the shape and angle of stiffeners were considered as the main parameters were tested under monotonic loading. Rectangular, triangular and AISC types of stiffener were tested under monotonic loading. The experimental results indicated that when the height of the stiffener is equal to or higher than the length of the stiffener, the shape of the stiffener does not have an influence on the behavior. A numerical study using the finite element tool ABAQUS was carried out in order to further investigate the effects of the stiffener shapes. In this case, the height is considered less than the length of the stiffener. Moreover, the shape of the stiffeners was investigated with the different thicknesses of the stiffener. The simulation findings revealed that when the height of the stiffener is less than the length of the stiffener, the shape of the stiffener significantly affects the plastic capacity. Based on the numerical and experimental results, it is recommended to use the triangular shape of the stiffener when height is equal to or higher than the length of the stiffener while it is recommended to utilize the rectangular shape of the stiffener when height is less than the length of the stiffener.