Istanbul, Turkey
Istanbul, Turkey

Yıldız Technical University is a technical university dedicated to engineering science and is one of the most prominent educational institutions in Istanbul, Turkey. The central campus lies within the Beşiktaş district. The new Davutpaşa campus lies within the Esenler district. 10 faculty, 3 vocational schools, and 2 institue. Wikipedia.


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Grant
Agency: Cordis | Branch: FP7 | Program: CSA-SA | Phase: INCO.2013-9.1 | Award Amount: 1.13M | Year: 2013

ETRERA 2020 - Empowering Trans-mediterranean Renewable Energy Research Alliance for 2020 energy targets is a project aimed at face front the future energy needs in the Euro Mediterranean area by reinforcing creating a collaborative research/innovation network for supporting renewable energy sources (RES) technologies development and application, in accordance with EU policy addresses. The ETRERA2020 idea is to improve S&T and entrepreneurial relationships between European Member States and the neighbouring Mediterranean countries in the strategic field of renewable energy production, distribution and storage by a range of activities targeted to bridging the existing gap between research and innovation. ETRERA 2020 will address its efforts not on the societal challenge: Secure, clean and efficient energy in a general way, because this modus operandi will not bring any concrete result since it is too wide. It aims to focus on the below described specific technologies: wind, PV, grid connection and solar thermal.


Allahverdiyev A.M.,Yildiz Technical University
Future microbiology | Year: 2011

Nanotechnology is the creation of functional materials, devices and systems at atomic and molecular scales (1-100 nm), where properties differ significantly from those at a larger scale. The use of nanotechnology and nanomaterials in medical research is growing rapidly. Recently, nanotechnologic developments in microbiology have gained importance in the field of chemotherapy. Bacterial strains that are resistant to current antibiotics have become serious public health problems that raise the need to develop new bactericidal materials. Metal oxide nanoparticles, especially TiO(2) and Ag(2)O nanoparticles, have demonstrated significant antibacterial activity. Therefore, it is thought that this property of metal oxide nanoparticles could effectively be used as a novel solution strategy. In this review, we focus on the unique properties of nanoparticles, their mechanism of action as antibacterial agents and recent studies in which the effects of visible and UV-light induced TiO(2) and Ag(2)O nanoparticles on drug-resistant bacteria have been documented. In addition, from to previous results of our studies, antileishmanial effects of metal oxide nanoparticles are also demonstrated, indicating that metal oxide nanoparticles can also be effective against eukaryotic infectious agents. Conversely, despite their significant potential in antimicrobial applications, the toxicity of metal oxide nanoparticles restricts their use in humans. However, recent studies infer that metal oxide nanoparticles have considerable potential to be the first-choice for antibacterial and antiparasitic applications in the future, provided that researchers can bring new ideas in order to cope with their main problem of toxicity.


Simsek M.,Yildiz Technical University
Composite Structures | Year: 2010

Vibration of a functionally graded (FG) simply-supported beam due to a moving mass has been investigated by using Euler-Bernoulli, Timoshenko and the third order shear deformation beam theories. The material properties of the beam vary continuously in the thickness direction according to the power-law form. The system of equations of motion is derived by using Lagrange's equations. Trial functions denoting the transverse, the axial deflections and the rotation of the cross-sections of the beam are expressed in polynomial forms. The constraint conditions of supports are taken into account by using Lagrange multipliers. In this study, the effects of the shear deformation, various material distributions, velocity of the moving mass, the inertia, Coriolis and the centripetal effects of the moving mass on the dynamic displacements and the stresses of the beam are discussed in detail. To validate the present results, the dynamic deflections of the beam under a moving mass are compared with those of the existing literature and a comparison study for free vibration of an FG beam is performed. Good agreement is observed. The results show that the above-mentioned effects play a very important role on the dynamic responses of the beam and it is believed that new results are presented for dynamics of FG beams under moving loads which are of interest to the scientific and engineering community in the area of FGM structures. © 2009 Elsevier Ltd. All rights reserved.


Simsek M.,Yildiz Technical University
Composite Structures | Year: 2010

In this paper, non-linear dynamic analysis of a functionally graded (FG) beam with pinned-pinned supports due to a moving harmonic load has been performed by using Timoshenko beam theory with the von-Kármán's non-linear strain-displacement relationships. Material properties of the beam vary continuously in thickness direction according to a power-law form. The system of equations of motion is derived by using Lagrange's equations. Trial functions denoting transverse, axial deflections and rotation of the cross-sections of the beam are expressed in polynomial forms. The constraint conditions of supports are taken into account by using Lagrange multipliers. The obtained non-linear equations of motion are solved with aid of Newmark- β method in conjunction with the direct iteration method. In this study, the effects of large deflection, material distribution, velocity of the moving load and excitation frequency on the beam displacements, bending moments and stresses have been examined in detail. Convergence and comparison studies are performed. Results indicate that the above-mentioned effects play a very important role on the dynamic responses of the beam, and it is believed that new results are presented for non-linear dynamics of FG beams under moving loads which are of interest to the scientific and engineering community in the area of FGM structures. © 2010 Elsevier Ltd.


Simsek M.,Yildiz Technical University
Nuclear Engineering and Design | Year: 2010

In this paper, fundamental frequency analysis of functionally graded (FG) beams having different boundary conditions is analyzed within the framework of the classical, the first-order and different higher-order shear deformation beam theories. The material properties of the beams vary continuously in the thickness direction according to the power-law form. Two types of formulation are developed. In the first formulation, total bending rotation measured on the beam middle surface is taken as unknown function whereas the shear rotation measured on the beam middle surface is taken as unknown function in the second formulation. The frequency equation is obtained by using Lagrange's equations and the boundary conditions of beams are satisfied with Lagrange multipliers. The unknown functions denoting the axial and the transverse deflections, the bending and the shear rotations of the cross-section of the beam are expressed in the polynomial form. In this study, the effects of slenderness ratio, material variations, the different formulations and the beam theories on the fundamental frequencies are examined. It is believed that the tabulated results will be a reference with which other researchers can compare their results. © 2009 Elsevier B.V. All rights reserved.


Bildirici M.E.,Yildiz Technical University
Biomass and Bioenergy | Year: 2013

This paper investigates the short-run and long-run causality analysis between biomass energy consumption and economic growth in the selected 10 developing and emerging countries by using the Autoregressive Distributed Lag bounds testing (ARDL) approach of cointegration and error correction models. It covers annual data from 1980 to 2009. The cointegration test results show that there is cointegration between the biomass energy consumption and the economic growth in nine of the ten countries (Argentina, Bolivia, Cuba, Costa Rica, El Salvador, Jamaica, Nicaragua, Panama, Paraguay, Peru). The cointegration test results show that there is no cointegration between the biomass energy consumption and the economic growth in one of the ten countries (Paraguay). © 2012 Elsevier Ltd.


Ayat B.,Yildiz Technical University
Energy | Year: 2013

Wave energy potential of the Eastern Mediterranean Sea Basin was assessed and characterized. Wave fields obtained from 3rd generation spectral wave model for years 1994-2009 by using wind data from European Center for Medium-Range Weather Forecasts (ECMWF) were used in order to calculate the wave powers. Wave model was calibrated using the wave measurements conducted at three different stations. Wave model simulated the wave characteristics such as significant wave heights (Hs) and mean wave periods (Tm) with high accuracy. Wave power atlas was generated based on 15-year time-averaged wave data. Also wave power roses and distribution tables in means of periods and heights for different regions were presented. Mean wave power found to be below 2kW/m along the coasts of the whole model area. The most energetic coast of the Southern Mediterranean Basin is Egyptian coastlying between Nile Delta and the Libya border with a potential of above 4kW/m. Some regions along the coasts of some Greek Islands also have potential above 4kW/m within the Aegean Sea Basin. The eastern part of the model area is found to be the least energetic. The most energetic sea states have significant wave heights between 1 and 4m and wave energy periods between 4 and 8s. Seasonal trends were also investigated in this study. The mean wave power in winter is roughly 2 times larger than annual mean. © 2013 Elsevier Ltd.


Simsek M.,Yildiz Technical University
Composites Part B: Engineering | Year: 2014

In this paper, a non-classical beam model based on the Eringen's nonlocal elasticity theory is proposed for nonlinear vibration of nanobeams with axially immovable ends. This non-classical (nonlocal) beam model incorporates the length scale parameter (nonlocal parameter) which can capture the small scale effect. The Hamilton's principal is employed to derive the governing equations and the related boundary conditions together with Euler-Bernoulli beam theory and the von-Kármán's nonlinear strain-displacement relationships. An approximate analytical solution is obtained for the nonlinear frequency of the nanobeam by utilizing the Galerkin method and He's variational method. In the numerical results, the ratio of nonlinear frequency to linear frequency is presented for three different boundary conditions. The effect of nonlocal parameter on the nonlinear frequency ratio is examined. Also, some illustrative examples are also presented to verify the present formulation and solutions. Good agreement is observed. These results can be used as benchmark for future studies. © 2013 Elsevier Ltd. All rights reserved.


In the present manuscript, a non-classical beam theory is developed for the static and nonlinear vibration analysis of microbeams based on a three-layered nonlinear elastic foundation within the framework of the modified couple stress theory and Euler-Bernoulli beam theory together with the von-Kármán's geometric nonlinearity. This non-classical beam model incorporates the length scale parameter which can account for the small size effect. By using the Hamilton's principle, the equations of motion and the boundary conditions of the problem are derived. The nonlinear partial differential equation governing the motion of the system is reduced to the nonlinear ordinary differential equation with the help of the Galerkin discretization technique. He's variational method is then applied for the first time to obtain approximate analytical expressions for the nonlinear frequency of the microbeams with pinned-pinned and clamped-clamped end conditions. Static analysis is also performed for uniformly distributed load. Some illustrative numerical examples are presented in order to investigate the influences of the length scale parameter and the stiffness coefficients of the nonlinear foundation on the static deflection and the ratio of nonlinear frequency to linear frequency (the nonlinear frequency ratio). Comparison studies are also performed to verify the present formulation and solutions. Close agreement is observed. © 2014 Elsevier Ltd.


The use of ethanol-diesel blends in diesel engines without any modifications negatively affects the engine performance and NOx emissions. However, steam injection method decreases NOx emissions and improves the engine performance. In this study, steam injection method is applied into a single cylinder, four-stroke, direct injection, naturally aspirated diesel engine fueled with ethanol-diesel blend in order improve the performance and NOx emissions by using two-zone combustion model for 15% ethanol addition and 20% steam ratios at full load condition. The results obtained are compared with conventional diesel engine (D), steam injected diesel engine (D + S20), diesel engine fueled with ethanol-diesel blend (E15) and steam injected diesel engine fueled with ethanol-diesel blend (E15 + S20) in terms of performance and NO emissions. The results showed that as NO emissions considerably decrease the performance significantly increases with steam injection method. © 2013 Elsevier Ltd. All rights reserved.

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