Thermal buckling load optimization of laminated plates with different intermediate line supports

Umut Topal 국제구조공학회 2012 Steel and Composite Structures, An International J Vol.13 No.3

This paper deals with critical thermal buckling load optimization of symmetrically laminated four layered angle-ply plates with one or two different intermediate line supports. The design objective is the maximization of the critical thermal buckling load and a design variable is the fibre orientation in the layers. The first order shear deformation theory and nine-node isoparametric finite element model are used for the finite element solution of the laminates. The modified feasible direction (MFD) method is used for the optimization routine. For this purpose, a program based on FORTRAN is used. Finally, the numerical analysis is carried out to investigate the effects of location of the internal line supports, plate aspect ratios and boundary conditions on the optimal designs and the results are compared.

Influence of asphalt removal on operational modal analysis of Egebækvej Bridge

Umut Yıldırım 국제구조공학회 2023 Smart Structures and Systems, An International Jou Vol.31 No.2

Using the most up-to-date system identification methods in both time and frequency domains, the dynamic monitoring data from the reinforced concrete Egebaekvej Bridge near Holte, Denmark, is examined in this investigation. The bridge was erected in the 1960s and was still standing during test campaign before demolishing. The ARTeMIS Modal was adopted to derive the modal parameters from ambient vibration data. Several Operational Modal Analysis (OMA) approaches were applied, including Enhanced Frequency Domain Decomposition (EFDD), Curve-fit Frequency Domain Decomposition (CFDD), and Frequency Domain Decomposition (FDD). Afterward, Principal Component (SSI-PC), Unweighted Principal Component (SSI-UPC) Stochastic Subspace Identification methods were utilized. Danish engineering consulting company, COWI with the allowance of the bridge contractor BARSLUND, allow the researcher for this experimental test to demonstrate the impact of OMA applications.

Application of a new extended layerwise approach to thermal buckling load optimization of laminated composite plates

Umut Topal 국제구조공학회 2013 Steel and Composite Structures, An International J Vol.14 No.3

This paper deals with the applicability of a new extended layerwise optimization method for thermal buckling load optimization of laminated composite plates. The design objective is the maximization of the critical thermal buckling of the laminated plates. The fibre orientations in the layers are considered as design variables. The first order shear deformation theory (FSDT) is used for the finite element solution of the laminates. Finally, the numerical analysis is carried out to show the applicability of extended layerwise optimization algorithm of laminated plates for different parameters such as plate aspect ratios and boundary conditions.

Mechanisms of immune tolerance to allergens in children

Umut C. Kucukseze,Cevdet Ozdemir,Mübeccel Akdis,Cezmi A. Akdis 대한소아청소년과학회 2013 Clinical and Experimental Pediatrics (CEP) Vol.56 No.12

Because the prevalence of allergic diseases has significantly increased in recent years, understanding the causes and mechanisms of these disorders is of high importance, and intense investigations are ongoing. Current knowledge pinpoints immune tolerance mechanisms as indispensable for healthy immune response to allergens in daily life. It is evident that development and maintenance of allergenspecific T cell tolerance is of vital importance for a healthy immune response to allergens. Such tolerance can be gained spontaneously by dose-dependent exposures to allergens in nature or by allergen-specific immunotherapy. Allergen-specific immunotherapy induces regulatory T cells with the capacity to secrete interleukin-10 and transforming growth factor-β, limits activation of effector cells of allergic inflammation (such as mast cells and basophils), and switches antibody isotype from IgE to the noninflammatory type IgG4. Although allergen-specific immunotherapy is the only method of tolerance induction in allergic individuals, several factors, such as long duration of treatment,compliance problems, and life-threatening side effects, have limited widespread applicability of this immunomodulatory treatment. To overcome these limitations, current research focuses on the introduction of allergens in more efficient and safer ways. Defining the endotypes and phenotypes of allergic diseases might provide the ability to select ideal patients, and novel biomarkers might ensure new custom-tailored therapy modalities.

Pareto optimum design of laminated composite truncated circular conical shells

Umut Topal 국제구조공학회 2013 Steel and Composite Structures, An International J Vol.14 No.4

This paper deals with multiobjective optimization of symmetrically laminated composite truncated circular conical shells subjected to external uniform pressure load and thermal load. The design objective is the maximization of the weighted sum of the critical buckling load and fundamental frequency. The design variable is the fibre orientations in the layers. The performance index is formulated as the weighted sum of individual objectives in order to obtain optimal solutions of the design problem. The first-order shear deformation theory (FSDT) is used in the mathematical formulation of laminated truncated conical shells. Finally, the effect of different weighting factors, length-to-radius ratio, semi-cone angle and boundary conditions on the optimal design is investigated and the results are compared.

Assessing the Effects of Climate Change on Monthly Precipitation: Proposing of a Downscaling Strategy through a Case Study in Turkey

Umut Okkan 대한토목학회 2015 KSCE Journal of Civil Engineering Vol.19 No.4

The forecasting of future precipitation can be considered by using the outputs of the General Circulation Models (GCMs). In the study, a downscaling strategy was improved to forecast monthly precipitation over Tahtali watershed in Turkey for climate change scenarios using neural networks. First, predictor variables, which represent the monthly areal precipitation of watershed, were selected from the NCEP/NCAR reanalysis data set with the help of correlation and mutual information analyses. The study of the predictor selection showed that large scale precipitation at surface, air temperature at 850 hPa, and geopotential height at 200 hPa are the explanatory variables for downscaling. When the statistical performance measures were investigated, developed downscaling model trained with selected predictors was found satisfactory and was applied to simulate the future projections of selected two GCMs; namely, ECHAM5 and HADCM3. Finally, the simulation results were examined to assess the possibility of climate change effect on precipitation in the study area.

Buckling load optimization of laminated plates via artificial bee colony algorithm

Umut Topal,Hasan Tahsin Öztürk 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.52 No.4

In this present work, Artificial Bee Colony Algorithm (ABCA) is used to optimize the stacking sequences of simply supported antisymmetric laminated composite plates with criticial buckling load as the objective functions. The fibre orientations of the layers are selected as the optimization design variables with the aim to find the optimal laminated plates. In order to perform the optimization based on the ABCA, a special code is written in MATLAB software environment. Several numerical examples are presented toillustrate this optimization algorithm for different plate aspect ratios, number of layers and load ratios.

Shear buckling analysis of cross-ply laminated plates resting on Pasternak foundation

Umut Topal,Ebrahim Nazarimofrad,Seyed Ebrahim Sadat Kholerdi 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.3

This paper presents the shear buckling analysis of symmetrically laminated cross-ply plates resting on Pasternak foundation under pure in-plane uniform shear load. The classical laminated plate theory is used for the shear buckling analysis of laminated plates. The Rayleigh-Ritz method with novel plate shape functions is proposed to solve the differential equations and a computer programming is developed to obtain the shear buckling loads. Finally, the effects of the plate aspect ratios, boundary conditions, rotational restraint stiffness, translational restraint stiffness, thickness ratios, modulus ratios and foundation parameters on the shear buckling of the laminated plates are investigated.

Dissident Voices: Women, Minority Status, and Criticism of the Nationalist Turkish State

Umut ÖZKALELI 이화여자대학교 아시아여성학센터 2013 Asian Journal of Women's Studies(AJWS) Vol.19 No.3

This paper analyses the ways in which women’s various minority positions serve as critical standpoints for deconstructing exclusionary nationalisms in Turkey, and offers some alternatives. After a brief analysis of categories of Turkish nationalism, an analysis of field data is presented, which discusses examples of how women critically engage with nationalism. Interviews with 45 women from different social locations stress the richness and intersectionality of identity. Presenting women’s powerful dissenting voices can contribute to the literature that seeks to create alternatives to exclusionary nationalisms. The paper argues that women’s vocal dissent serves as a necessary participatory aspect of democratization in Turkey.

Dynamic analysis for high-speed train hollow power axle

Umut Kınıt,Ferhat Dikmen 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.2

This study was carried out to find the forces acting on a Siemens Velaro D type high-speed train hollow power axle commissioned by Türkiye Cumhuriyeti Devlet Demiryolları (TCDD) to examine the dynamic loads created by these forces and to understand whether these shafts are safe in terms of continued strength. Track shift forces were found for the highspeed train, and according to these forces the net axle force ratio (L/V) was calculated depending on the speed increase. These data were compared with the experimental results of the Federal Railroad Administration (American FRA) and German Railways. In this study, after determining the compatibility of the calculated results with the experimental data, various analyses such as different road conditions, load on the axle for full vehicles, variation of vertical load, dynamic factor, safety factor and continuous strength calculation for the most dangerous section were carried out. Considering these analyses, while the static load is 148 kN in the vehicle loaded condition, this load increases to 153 kN in the vehicle loaded condition and at a speed of 70 m/s. For this reason, it would be wrong to use the static load created by the weight of the vehicle alone in the classical continuous strength calculation. The dynamic load created by the vehicle travel speed must be added to the calculations.