Response of forced Euler-Bernoulli beams using differential transform method

Seval Catal 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.42 No.1

In this paper, forced vibration differential equations of motion of Euler-Bernoulli beams with different boundary conditions and dynamic loads are solved using differential transform method (DTM), analytical solutions. Then, the modal deflections of these beams are obtained. The calculated modal deflections using DTM are represented in tables and depicted in graphs and compared with the results of the analytical solutions where a very good agreement is observed.

Compression of hollow-circular fiber-reinforced rubber bearings

Seval Pinarbasi,Fuad Okay 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.38 No.3

Earlier studies on hollow-circular rubber bearings, all of which are conducted for steelreinforced bearings, indicate that the hole presence not only decreases the compression modulus of the bearing but also increases the maximum shear strain developing in the bearing due to compression, both of which are basic design parameters also for fiber-reinforced rubber bearings. This paper presents analytical solutions to the compression problem of hollow-circular fiber-reinforced rubber bearings. The problem is handled using the most-recent formulation of the “pressure method”. The analytical solutions are, then, used to investigate the effects of reinforcement flexibility and hole presence on bearing’s compression modulus and maximum shear strain in the bearing in view of four key parameters: (i) reinforcement extensibility, (ii) hole size, (iii) bearing’s shape factor and (iv) rubber compressibility. It is shown that the compression stiffness of a hollow-circular fiber-reinforced bearing may decrease considerably as reinforcement flexibility and/or hole size increases particularly if the shape factor of the bearing is high and rubber compressibility is not negligible. Numerical studies also show that the existence of even a very small hole can increase the maximum shear strain in the bearing significantly, which has to be considered in the design of such annular bearings.

Experimental study on partially-reinforced steel RHS compression members

Seval Pinarbasi 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.63 No.3

This paper presents an experimental study on the behavior of axially-loaded steel RHS (rectangular hollow section) compression members that are partially reinforced along their lengths with welded steel plates. 28 slender column tests were carried out to investigate the effects of the slenderness ratio of the unreinforced member and the ratio of the reinforced length of the member to its entire length. In addition to the slender column tests, 14 stub-column tests were conducted to determine the basic mechanical properties of the test specimens under uniform compression. Test results show that both the compressive strength and stiffness of an RHS member can be increased significantly compared to its unreinforced counterpart even when only the central quarter of the member is reinforced. Based on the limited test data, it can be concluded that partial reinforcement is, in general, more effective in members with larger slenderness ratios. A simple design expression is also proposed to predict the compressive strength of RHS columns partially reinforced along their length with welded steel plates by modifying the provisions of AISC 360-10 to account for the partial reinforcement.

Buckling analysis of semi-rigid connected and partially embedded pile in elastic soil using differential transform method

Seval Catal 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.52 No.5

The parts of semi-rigid connected and partially embedded piles in elastic soil, above the soil and embedded in the soil are called the first region and second region, respectively. The upper end of the pile in the first region is supported by linear-elastic rotational spring. The forth order differential equations of both region for critical buckling load of partially embedded and semi-rigid connected pile with shear deformationare established using small-displacement theory and Winkler hypothesis. These differential equations are solved by differential transform method (DTM) and analytical method and critical buckling loads of semirigid connected and partially embedded pile are obtained, results are given in tables and graphs are presentedfor investigating the effects of relative stiffness of the pile and flexibility of rotational spring.

Analysis of fiber-reinforced elastomeric isolators under pure "warping"

Seval Pinarbasi,Yalcin Mengi 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.61 No.1

As a relatively new type of multi-layered rubber-based seismic isolators, fiber-reinforced elastomeric isolators (FREIs) are composed of several thin rubber layers reinforced with flexible fiber sheets. Limited analytical studies in literature have pointed out that "warping" (distortion) of reinforcing sheets has significant influence on buckling behavior of FREIs. However, none of these studies, to the best knowledge of authors, has investigated their warping behavior, thoroughly. This study aims to investigate, in detail, the warping behavior of strip-shaped FREIs by deriving advanced analytical solutions without utilizing the commonly used “pressure”, incompressibility, inextensibility and the "linear axial displacement variation through the thickness" assumptions. Studies show that the warping behavior of FREIs mainly depends on the (i) aspect ratio (shape factor) of the interior elastomer layers, (ii) Poisson’s ratio of the elastomer and (iii) extensibility of the fiber sheets. The basic assumptions of the "pressure" method as well as the commonly used incompressibility assumption are valid only for isolators with relatively large shape factors, strictly incompressible elastomeric material and nearly inextensible fiber reinforcement.

Optimization of β-Galactosidase Production in Stirred Tank Bioreactor Using Kluyveromyces lactis NRRL Y-8279

Seval Da?ba?lı,Yekta Goksungur 한국식품과학회 2009 Food Science and Biotechnology Vol.18 No.6

This paper investigates the production and optimization of β-galactosidase enzyme using synthetic medium by Kluyveromyces lactis NRRL Y-8279 in stirred tank bioreactor. Response surface methodology was used to investigate the effects of fermentation parameters on β-galactosidase enzyme production. Maximum specific enzyme activity of 4,622.7 U/g was obtained at the optimum levels of process variables (aeration rate 2.21 vvm, agitation speed 173.4 rpm, initial sugar concentration 33.8 g/ℓ, incubation time 24.0 hr). The optimum temperature and pH of the β-galactosidase enzyme produced under optimized conditions were 37℃ and pH 7.0, respectively. The enzyme was stable over a pH range of 6.0-7.5 and a temperature range of 25-37℃. The Km and Vmax values for O-nitrophenol-β-D-galactopyranoside (ONPG) were 1.20 mM and 1,000 μ㏖/minㆍ㎎ protein, respectively. The response surface methodology was found to be useful in optimizing and determining the interactions among process variables in β-galactosidase enzyme production. Hence, this study fulfills the lack of using mathematical and statistical techniques in optimizing the β-galactosidase enzyme production in stirred tank bioreactor.

In the shadow of gender : Wives of prisoners in Turkey

Seval BEKIROĞLU,Seda ATTEPE ÖZDEN,Arzu İÇAĞASIOĞLU ÇOBAN 이화여자대학교 한국여성연구원 2022 Asian Journal of Women's Studies(AJWS) Vol.28 No.2

Imprisonment of men can many negative economic, social and psychological effects on prisoners, their spouses and children. It is important to evaluate these and understand the gender-related experiences of wives of prisoners. So, we conducted three focus group discussions (FGDs) with 14 women in Turkey. We used an inductive content analysis approach and identified four relevant themes as follows: (1) women’s roles (as spouse, mother and social beings), (2) poverty, (3) stigma and exclusion, and (4) coping mechanisms. We noted that our respondents faced economic problems, difficulties in raising children, social exclusion, and emotional difficulties. In Turkey, gender norms and insufficient policies and services for such women exacerbate such issues. It is therefore important to develop gender-sensitive services that would empower and support them.

IMAGE OF INTEREST : Fluorodeoxyglucose-positron emission tomography/computed tomography imaging of squamous cell carcinoma arising in a meningomyelocele

( Seval Erhamamci ),( Mehmet Reyhan ),( Nebil Bal ) 대한내과학회 2016 The Korean Journal of Internal Medicine Vol.31 No.2

Analysis of free vibration of beam on elastic soil using differential transform method

Catal, Seval Techno-Press 2006 Structural Engineering and Mechanics, An Int'l Jou Vol.24 No.1

Differential transform method (DTM) for free vibration analysis of both ends simply supported beam resting on elastic foundation is suggested. The fourth order partial differential equation for free vibration of the beam resting on elastic foundation subjected to bending moment, shear and axial compressive load is obtained by using Winkler hypothesis and small displacement theory. It is assumed that the material is linear-elastic, and that axial load and modulus of subgrade reaction to be constant. In the analysis, shear and axial load effects are considered. The frequency factors of the beam are calculated by using DTM due to the values of relative stiffness; the results are presented in graphs and tables.

Buckling analysis of partially embedded pile in elastic soil using differential transform method

Catal, Seval,Catal, Hikmet Huseyin Techno-Press 2006 Structural Engineering and Mechanics, An Int'l Jou Vol.24 No.2

The parts of pile, above the soil and embedded in the soil are called the first region and second region, respectively. The forth order differential equations of both region for critical buckling load of partially embedded pile with shear deformation are obtained using the small-displacement theory and Winkler hypothesis. It is assumed that the behavior of material of the pile is linear-elastic and that axial force along the pile length and modulus of subgrade reaction for the second region to be constant. Shear effect is included in the differential equations by considering shear deformation in the second derivative of the elastic curve function. Critical buckling loads of the pile are calculated for by differential transform method (DTM) and analytical method, results are given in tables and variation of critical buckling loads corresponding to relative stiffness of the pile are presented in graphs.