Turkish Academy Of Sciences

Ankara, Turkey

Turkish Academy Of Sciences

Ankara, Turkey

The Turkish Academy of science is an autonomous scholarly society acting to promote scientific activities in Turkey. Although it is attached to the office of the Prime Minister and is largely funded by the government, it maintains financial and administrative autonomy. The academy is headquartered in Ankara.In addition to conferring awards and fellowships to distinguished scientists, the academy is also responsible with determining scientific priority areas and proposing policies and needed changes in legislation to the government. The implementation and management of actual research programmes is carried out by The Scientific and Technological Research Council of Turkey .Traditionally, the academy elected its own members, but beginning in November 2011, the Turkish government under the leadership of Recep Tayyip Erdoğan announced that it would take over new appointments, and appointed 100 new members. Accordingly, over 60 of the existing old members of the academy got resigned. Its current president is Ahmet Cevat ACAR who is prestigious professor in business academics and the former vice rector of the Istanbul University. Wikipedia.

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Kahvec G.,Turkish Academy Of Sciences
Turkish Journal of Agriculture and Forestry | Year: 2017

Central Anatolia has semiarid ecological conditions that limit tree growth. In addition, long-term human activity has resulted in degradation of existing forests lands. Current forest cover mainly includes oak, juniper, and pine species. In this study, the distribution and present state of Pinus nigra L. and Quercus spp. (Quercus cerris L. and Quercus pubescens L.) mixed stands, and the relationship between different environmental factors and abundance of oaks and pines were analyzed. The results indicate that interactions of environmental variables and human disturbance may have influenced the frequency and abundance of species in the region. © TÜBITAK.

Bilgin M.B.,Turkish Academy Of Sciences | Meran C.,Pamukkale University
Materials and Design | Year: 2012

In this study, the effects of tool rotational speed and traverse speed on welding of AISI 430 (X6Cr17, material number 1.4016) ferritic stainless steels by friction stir welding method are examined. Two specimens with dimension of 3×100×200mm were joined in butt position. Tool rotational speeds were determined to be 560-1400min-1 and traverse speeds as 80-200mm/min. During the studies, tool pressure force 3.5kN and tool angle of 0° was kept constant. Hard metal carbide (WC-Co hard metal identified as K10) with equilateral triangle tip profile was used as the tool material. Determination of the tool advance speeds related to the tool rotation speeds giving the best-looking weld seals with acceptable values of mechanical properties was aimed. During welding of the specimens joined in butt position, the temperature change due to time and variation of the pressure force applied on welded specimens by the tool shoulder has been recorded. It has been observed that the best mechanical resistance values were obtained at tool rotational speed of 1120min-1 through five tool rotational speeds (560-1400). Also it has been observed that the best mechanical resistance values were obtained at traverse speed of 125mm/min through five traverse speeds (80-200) with the constant tool pressure force of 3.5kN and tool angle of 0°. © 2011 Elsevier Ltd.

Hocaoglu S.M.,TUBITAK - Marmara Research Center | Insel G.,Technical University of Istanbul | Cokgor E.U.,Technical University of Istanbul | Orhon D.,Technical University of Istanbul | Orhon D.,Turkish Academy Of Sciences
Bioresource Technology | Year: 2011

Effect of low dissolved oxygen on simultaneous nitrification and denitrification was evaluated in a membrane bioreactor treating black water. A fully aerobic membrane bioreactor was operated at a sludge age of 60. days under three low dissolved oxygen (DO) levels below 0.5. mg/L. It sustained effective simultaneous nitrification/denitrification for the entire observation period. Nitrification was incomplete due to adverse effects of a number of factors such as low DO level, SMPs inhibition, alkalinity limitation, etc. DO impact was more significant on denitrification: Nitrate was fully removed at low DO level but the removal was gradually reduced as DO was increased to 0.5. mg/L. Nitrogen removal remained optimal within the DO range of 0.15-0.35. mg/L. Experimental results were calibrated and simulated by model evaluation with the same model coefficients. The model defined improved mass transfer with lower affinity coefficients for oxygen and nitrate as compared to conventional activated sludge. © 2010 Elsevier Ltd.

Kabak M.,Turkish Academy Of Sciences | Burmaoglu S.,Turkish Academy Of Sciences | Kazancoglu Y.,Izmir University of Economics
Expert Systems with Applications | Year: 2012

Personnel selection is an important process in management. Sniper selection as a subset of personnel selection contains different characteristics compared to selection of other personnel. The multi criteria nature and the presence of both qualitative and quantitative factors make it considerably more complex. This study proposes a fuzzy hybrid multicriteria decision making approach enabling the combination of both qualitative and quantitative factors. The use of a combination of Fuzzy ANP, Fuzzy TOPSIS, Fuzzy ELECTRE techniques, proposing a MCDM approach for sniper selection, and applying these to a real case are the unique features of this study. © 2011 Elsevier Ltd. All rights reserved.

This study investigates the low velocity impact properties such as damage thresholds, critical energy thresholds and damage process of laminated composites. Damage thresholds of Hertzian failure and main failure corresponding to woven and unidirectional Glass Fiber Reinforced Polymer laminates in varying thicknesses from 2. mm to 8. mm are determined through impact tests with nominal impact energies of 4, 6, and 8. J/layer. Hertzian failure and main failure thresholds of a composite laminate with a particular thickness remain substantially constant with the nominal and incipient impact energies. Energy profile and normalized energy profile diagrams are used to find out the penetration and perforation thresholds as well as explaining the correlation between the threshold energies and damage process of the laminates. Dissipated energy by a laminate is determined using a second order polynomial regression based on the relationship between energy dissipation and impact energy of data points before penetration. Penetration and perforation energies increase non-linearly with the thickness and thickness dependence is expressed using a power regression. Test results related to damage thresholds, threshold energies and effective damage area reveal that unidirectional laminates possess lower impact damage resistance and hence are more sensitive to impact damage. © 2015 Elsevier Ltd.

Eryilmaz S.,Atilim University | Sarikaya K.,Turkish Academy Of Sciences
Proceedings of the Institution of Mechanical Engineers, Part O: Journal of Risk and Reliability | Year: 2014

This article is concerned with the reliability analysis of a weighted-k-out-of-n:G system consisting of two types of components. The system is assumed to have n components which are classified into two groups with respect to their weight and reliability, and it is assumed to operate if the total weight of all working components exceeds a prespecified threshold k. The reliability properties of such a system are studied. The optimal values of the number of components in each group are also determined under a minimum required reliability by minimizing the total acquisition cost. © IMechE 2013.

Aplak H.S.,Turkish Academy Of Sciences | Sogut M.Z.,Turkish Military Academy
Energy Conversion and Management | Year: 2013

Intensive energy consuming industrial sectors are the most important actors on global climate change which natural habitat and the environment faced. In this study, by the scope of energy management, decision-making process of the industry and the environment are evaluated in a game theoretic approach. Industry and environment are considered as two players which have conflicting objectives and try to find optimal strategies in governing energy policy. According to concept of study, while industry tries to maintain the sustainability of production with the strategies of fossil fuel, renewable energies, energy recovery and nuclear energy usage, environment exhibits reactive approach to ensure its sustainability. In the flow of study, players' strategies are analyzed by using Multi-Criteria Decision Making (MCDM) methods and by calculating performance efficiency values of strategies, game payoff matrix is obtained. Finally, optimal strategies are found for both industry and environment in orienting their energy policy and results are evaluated. According to results of the payoff matrix, the equilibrium point is the cell (2, 1) with the values of 0.5324 and 0.5619. This implies that the environment develops protective reflexes for sustainable nature in case of using renewable energy in industry. © 2013 Elsevier Ltd. All rights reserved.

Evci C.,Turkish Academy Of Sciences | Gulgec M.,Cankaya University
International Journal of Impact Engineering | Year: 2012

Due to the improved impact performance characteristics, composites are widely used in engineering and military applications to absorb the impact energy. Determination of impact response of composite materials provides the engineer and the manufacturer with critical knowledge to understand the failure criteria, initiation of the first failure and damage growth through the laminates. This study covers the investigation of impact damage growth and determination of Hertzian failure and maximum force thresholds in three different types of composites. Unidirectional E-Glass, woven E-Glass and woven Aramid composite samples with dimensions of 100 × 100 mm are subjected to low velocity impact with an instrumented impact test system. Rebound, on-set of perforation and perforation limits of composites are found out. Also, energy profile diagrams of both unidirectional and plain weave E-Glass composites are obtained. According to test results, woven composites are found to be superior to unidirectional composites in the protection limit of low velocity impact. It is also observed that damage growth in woven composites is restricted within a smaller area. Impact tests conclude that strength of the composite materials under dynamic loading increases considerably compared to static loading case as a result of strain rate sensitivity. © 2011 Elsevier Ltd. All rights reserved.

Ciggin A.S.,Technical University of Istanbul | Insel G.,Technical University of Istanbul | Majone M.,University of Rome La Sapienza | Orhon D.,Technical University of Istanbul | Orhon D.,Turkish Academy Of Sciences
Bioresource Technology | Year: 2012

The study investigated the effect of feeding regime and sludge age on acetate utilization. Parallel sequencing batch reactors (SBRs) were operated at steady-state with pulse and continuous feeding of acetate at sludge ages of 8 and 2days. Acetate was always partially converted to poly-β-hydroxybutyrate (PHB). The adopted model remained equally applicable to oxygen uptake rate and PHB profiles reflecting different feeding regimes and culture history. Sludge age was significant on the rate parameters of storage and direct growth (k STO, μ H1), while the feeding regime affected half saturation coefficients (K STO, K S1). Changing the sludge age from 8days to 2days reduced the k STO value from 8.0day -1 to 6.5day -1 and increased the corresponding μ H1 value from 1.5day -1 to 2.5day -1, regardless of the feeding regime; conversely, changing from pulse to continuous feeding reduced K STO while increasing K S for the SBR operation at the same sludge age. © 2011 Elsevier Ltd.

Sari M.M.,Turkish Academy Of Sciences
Materials Chemistry and Physics | Year: 2013

Dopamine plays a crucial and essential role in the function of human metabolism. It is important to develop selective and sensitive materials for the detection of dopamine (DA) without the interference by coexisting compounds. In this study, fluorescein isothiocyanate (FITC) conjugated graphene oxide (GO) microsheets were developed and this system was used as a novel supporting matrix for adsorption based selective and sensitive detection of dopamine. Fluorescein isothiocyanate conjugated graphene oxide microsheets (FITC-GOs) showed high affinity to DA. Selectivity of FITC-GOs to DA is 31 and 28 times higher than that of coexisting molecules, ascorbic acid (AA) and uric acid (UA), respectively. Compared with DA, affinity of FITC-GOs to AA and UA is non-specific and can be negligible. Low detection limit of 2 × 10 -7 M (0.2 μM) for DA was obtained. All experiments were carried out in the neutral solutions at around physiological pH. This study provides a simple and easy method for selective and sensitive detection of dopamine in the mixture of other most abundant coexisting molecules that generally cause interference. © 2013 Elsevier B.V. All rights reserved.

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