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.

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.

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.

THE RELATIONS BETWEEN NULL GEODESIC CURVES AND TIMELIKE RULED SURFACES IN DUAL LORENTZIAN SPACE D³₁

( Yasin Unluturk ),( Suha Yilmaz ),( 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.

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>

A new replaceable fuse for moment resisting frames: Replaceable bolted reduced beam section connections

Yasin O. Özkılıç 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.35 No.3

This paper describes a new type of replaceable fuse for moment resisting frames. Column-tree connections with beam splice connections are frequently preferred in the moment resisting frames since they eliminate field welding and provide good quality. In the column-tree connections, a part of the beam is welded to the column in the shop and the rest of the beam is bolted with the splice connection in the field. In this study, a replaceable reduced beam section (R-RBS) connection is proposed in order to eliminate welding process and facilitate assembly at the site. In the proposed R-RBS connection, one end is connected by a beam splice connection to the beam and the other end is connected by a bolted end-plate connection to the column. More importantly is that the proposed R-RBS connection allows the replacement of the damaged R-RBS easily right after an earthquake. Pursuant to this goal, experimental and numerical studies have been undertaken to investigate the performance of the R-RBS connection. An experimental study on the RBS connection was used to substantiate the numerical model using ABAQUS, a commercially available finite element software. Additionally, five different finite element models were developed to conduct a parametric study. The results of the analysis were compared in terms of the moment and energy absorption capacities, PEEQ, rupture and tri-axiality indexes. The design process as well as the optimum dimensions of the R-RBS connections are presented. It was also demonstrated that the proposed R-RBS connection satisfies AISC criteria based on the nonlinear finite element analysis results.

Effects of Mn Content on Microstructure, Mechanical and Dry Sliding Wear Properties of Eutectic Al–Si–Cu Alloy

Yasin Alemdag,Murat Beder 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.12

In the present study, effects of Mn content on microstructure, hardness, tensile and dry sliding wear properties of eutecticAl–Si–Cu alloy in as cast-state were investigated. Mn addition to the eutectic alloy results in the formation of α-Al15Mn3Si2phase in its microstructure. It was found that hardness of eutectic alloy increases continuously with increasing Mn contentwhile its tensile strength and percentage elongation values decrease. It was also found that the friction coefficient and volumeloss of eutectic alloy decrease as Mn content increases. Amongst the alloys, the lowest friction coefficient is obtained withAl–12Si–3Cu–2Mn alloy yet the Al–12Si–3Cu–1Mn alloy exhibits the highest wear resistance. Formation of adhesion layer,its oxidation and delamination were observed to be main wear mechanisms of Al–12Si–3Cu–(0–2)Mn alloys. These findingsare explained in terms of formation of α-Al15Mn3Si2 phase, and its cracking tendency effect.

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.

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.

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.