Yayınlar
Koleksiyondaki öğeler
- MakaleYalnız künye2018Scopus SJRQ4Antioxidant potential of rosehip seed extract in stabilisation of flaxseed oil
Ilyasoglu, H.
The aim of this study was to evaluate the usage of rosehip seed powder (RSP) extract in flaxseed oil to retard lipid oxidation. The acetone extract of the RSP (500 mg kg-1; 1000 mg kg-1) was used. Synthetic antioxidant BHT (200 mg kg-1) was added into the flaxseed oil to evaluate the antioxidant potential of the RSP extract. The peroxide value (PV), TBARS value, and p-anisidine value (p-AV) of the flaxseed oil were analysed during 12 days of storage. The total oxidation (TOTOX) value was also calculated. The sample with the RSP (500 mg kg-1; 1000 mg kg-1) generally showed lower PV, p-AV, and TOTOX value than the control sample and sample with the BHT. These results indicated that the RSP may be used in edible oils to prevent lipid oxidation as a source of natural antioxidants.
- Kitap BölümüYalnız künye2019Investigation of the effects of the disasters occurred between 2010 and 2017 on the world economy
Turan, Melikşah; Oral, Vildan; Kaya, Afşin Ahmet
Introduction Disasters cause losses in various dimensions throughout the world. They lead to social, psychological, political and cultural changes as well as economic burdens for countries. People have been facing disasters since the beginning of human history. Information about disasters occurring in different parts of the world has been found in the oldest known records. Thousands of people have lost their lives in these disasters. (Akgiray et al., 2004: 77). Natural disasters cause significant economic losses and the loss of life for countries (Erkal and Degerliyurt, 2009). According to the statistics in Turkey, natural disasters result in economic losses equal to 1.1 % of Gross National Product each year (Aktürk and Albeni, 2002). However, considering indirect economic losses such as loss of production and unemployment, total loss is estimated to be greater than 1 % of gross national product (Erkal and Degerliyurt, 2009). It is possible to estimate the economic effects of the disasters by considering factors which are affected by the disasters. When the 1999 Marmara Earthquakes in Turkey is evaluated in terms of both loss of income and loss of national wealth, the total estimated cost is between 9 million dollars and 13 billion dollars according to the State Planning Organization of Turkey and 6-10 billion dollars according to the World Bank (Akgiray et al., 2004: 77). Estimations about the economic effects of the 1999 Marmara Earthquakes suggest the following figures: the reconstruction of damaged buildings is estimated….
- MakaleYalnız künye2019Scopus SJRQ1Circuit implementation of nano-scale TiO2 memristor using only metal-oxide-semiconductor transistors
Gul, Fatih
A metal-oxide-semiconductor (MOS)-based circuit model that emulates a TiO2 memristor is proposed in this study. First, a TiO2 (10-nm active layer thickness)-based memristor device was fabricated. The structural properties of the device were confirmed via energy dispersive X-ray spectroscopy. The memristive characteristics of the device were resolved by applying a time-dependent voltage. The typical pinched hysteresis memristive loops of the current-voltage curves were obtained. After physical implementation and characterization of the device, a circuit model was implemented using only four MOS transistors to emulate the fabricated TiO2 memristor. In addition to emulating the fabricated memristor, the proposed circuit model is suitable for use in general memristor-based applications. No active element or circuit blocks were used in the circuit to achieve memristive characteristics. The simulation and experimental results are in good agreement; moreover, the circuit is very simple compared to those presented in previous studies in the literature and it was able to emulate the fabricated memristor. All simulations were completed using 180 nm TSMC CMOS process parameters.
AtıfScopus38WoS35OpenAlex40
İncele - BildiriAçık Erişim2018Thermal modeling and verification of pv module temperature and energy yield using outdoor measurements for Ankara, Turkey
Tuncel, Bilge; Akinoglu, Bulent G.; Ozden, Talat; Balog, Robert S.
Ankara is in the Central Anatolia region of Turkey where the climate is dry-continental with an annual solar insolation of around 1750 kWh/m 2 . In the transition to renewable energy, detailed analyses are required to ensure effective and economic utilization of the available solar resource. An essential part of these analyses is to calculate expected energy yield. For photovoltaic (PV) systems, this includes the effect of temperature on the PV efficiency, which determines the power yield of the PV modules. In this study, a first-principles thermal modeling approach is improved by adding the speed and direction of wind across the PV module into a forced convection term as well as including the temperature dependency of the module conversion efficiency. The analytical model is based on the principle of conservation of energy and uses meteorological data that are readily available from most state meteorological services. The mathematical analysis is suitable to predict the performance of a proposed PV installation without the time and expense of installing and monitoring a pilot system. The mathematical model is compared against measured data from the METU-GUNAM Outdoor Test Facility in Ankara to validate the methodology. Preliminary analyses showed that the model performs well especially during sunrise and sunsets shoulders of the diurnal cycle with a deviation of only a few W/m 2 for the electrical power yield and about 2°C for the module temperature. However, these deviations could become as large as 12 W/m 2 and 8°C at solar noon which suggests that the model still requires further improvement. In general, this error was found to be less that obtained by using basic explicit correlation methods and offers the advantage that it can be used for other geographical environments for which insolation and meteorological data is available without needing to construct a test-site.
AtıfScopus6WoS4OpenAlex6İncele - MakaleYalnız künye2018Scopus SJRQ1Galileo satellite data contribution to GNSS solutions for short and long baselines
Yalvac, S.; Berber, M.
GALILEO (Europe's Global Navigation Satellite System) is going full speed ahead to achieve full constellation by 2020. Since GALILEO is currently an emerging system, the contribution of these satellites to GNSS (Global Navigation Satellite System) solutions needs to be investigated. For this purpose, GNSS data collected at three IGS (International GNSS Service) MGEX (Multi GNSS Experiment) stations are analyzed. For the analyses, GPS (Global Positioning System) only, GLONASS (Russia's Global Navigation Satellite System) only, GALILEO-only and combined solutions are tested and also effect of baseline length is examined. The results indicate that compared to GPS, GLONASS and ALL (GPS + GLONASS + GALILEO) solutions, GALILEO results vary greatly. When GALILEO observations are combined with other observations, the precision goes down. That is to say, for short baseline solution, GALILEO results fluctuate around 1 cm in the horizontal plane and in the vertical plane variations are mostly within 3–5 cm. For long baseline solution, GALILEO results are going up and down in the horizontal between 2 and 3 cm and in the vertical roughly 10 cm. In terms of accuracy, for short baseline solution, GALILEO-only solution is close to GPS-only solution; yet, we cannot say the same thing for long baseline solution.
AtıfScopus13WoS11OpenAlex12İncele - BildiriAçık Erişim2018Well-posedness of Neumann-type elliptic overdetermined problem with integral condition
Ashyralyyev, Charyyar; Çay, Aysel
The current paper is devoted to overdetermined elliptic problem with integral condition for derivatives. This overde-termined problem is converted to auxiliary nonlocal boundary value problem (ANBVP) with integral boundary condition. Well-posedness of abstract problem is established. Then, obtained results are used to obtain stability inequalities for solution of three Neumann-type inverse elliptic problems with integral condition to multidimensional differential equation.
AtıfScopus14WoS9OpenAlex16İncele - MakaleAçık Erişim2017Scopus SJRQ2Prevalence and comparing of some microbiological properties, somatic cell count and antibiotic residue of organic and conventional raw milk produced in Turkey
Ürkek, Bayram; Şengül, Mustafa; Erkaya, Tuba; Aksakal, Vecihi
The aim of this study was to investigate the effects of production systems and milk collection periods on the somatic cell count (SCC), some microbiological properties, total aerobic mesophilic bacteria (TAMB), coliform, Staphylococcus aureus (S. aureus), yeast and mould) and antibiotic residue of milk; in Turkey. Milk samples were collected from 9 conventional farms and 9 organic farms during one year time, at six different months (December 2013 to October 2014), and all farms were selected from the same geographical locations. All organically managed farms had organic production certificates given by the Republic of Turkey Ministry of Food, Agriculture and Livestock. The count of TAMB, coliform, and coagulase positive S. aureus were affected by production systems at the level of p<0.01; yeast and mold, and somatic cell count (SCC) were affected at the level of p<0.05. But, differences according to months were statistically significant only on TAMB (p<0.01) and coliform (p<0.05) counts. The general means of TAMB, coliform and yeast and mould counts of the organic milk (OM) were significantly lower (p<0.05), while the general means of SCC and coagulase positive S. aureus count of the OM was significantly higher (p<0.05) compared to conventional milk (CM). Antibiotic residue was determined in one of the CM sample and in two of the OM samples. Our study is the first research that compared conventional and organic milk in Turkey. This study indicated that the microbiological quality of OM was the higher in terms of TAMB, coliform and yeast and mould, whereas was the lower in relation to SCC and coagulase positive S. aureus counts. But, the quality of both milk types should be improved.
AtıfScopus10WoS8OpenAlex12
İncele - MakaleYalnız künye2018Scopus SJRQ4The effects of 4-Vinylcyclohexene diepoxide on gene expression in dog testes
Paksoy, Zahid
In this study, the effects of 4-Vinylcyclohexene diepoxide (VCD) on the testicular gene expression in dogs were investigated. Eighteen male dogs were used as material and were randomly allocated to 3 groups. The first group (n=6) was administered sesame oil by intraperitoneal (i.p.) route once a day for 8 days, and this group was served as a control. The second group (n=6) received 80 mg/kg VCD and the third (n=6) group was administered VCD (i.p.) at a dose of 320 mg/kg once daily for 8 days. The testes were removed on following day the last VCD administration. The testes were immediately placed in the RNA stabilization solution and stored at -20°C. Later mRNAs were obtained from tissue samples. After RNA isolation, the cDNAs were synthesized. Finally, MasterMix was prepared and gene expression levels were examined at the real-time PCR. The expression of B cell lymphoma 2 (Bcl-2), tumor suppressor protein (tp53), Bax, CASP2, CASP3, CASP8, CASP9 and β-actin were investigated in the all groups. Cross-group comparisons were made by using student t test. The tp53 gene expression in the second group was found to be higher compared to the control group. It was determined that the expression of Bcl-2 was reduced in the testes of animals treated with high-dose VCD. CASP-3 was found to be more expressed and CASP-9 was down-regulated in the third group. In addition, CASP-8 gene expression was significantly reduced in both treatment groups. As a result, it can be concluded that expression changes in the tp53, Bcl-2, CASP-3, CASP-8 and CASP-9 genes in the testes of male dogs may cause apoptotic changes with the VCD application.
AtıfScopus1İncele - Kitap BölümüYalnız künye2019Eu-China relations: Current and future challenges and opportunities
Uğur, Ömer
While EU-China relations are often characterized by a clear divergence of values and political norms, the scope and size of the relationship between the two sides in the past twenty-five years has been remarkable. The basis of this development lies in the considerable expansion of the economic interaction and substantial growth in trade between the two sides since the early 1990. Relations between the EU and China are now so dense as well as complex. In this study, development of the relations between the EU and China will be discussed and it will also be expressed why and how much this relation is significant for both parties. While doing this, the main factors that enable the relations between the EU and China and that prevent aforementioned relations to deepen will be discussed and opportunities, expectations and problems these bring forth will be mentioned. Thus, this study will try to provide an answer why the EU and China experience significant conflicts and even come across each other from time to time in the recent years will be answered.
- MakaleYalnız künye2018Scopus SJRQ1The Fabrication and MOSFET-Only Circuit Implementation of Semiconductor Memristor
Babacan, Yunus; Yesil, Abdullah; Gul, Fatih
In this paper, a ZnO-based semiconductor thin film memristor (300 nm in thickness) device is fabricated using metallic top and bottom electrodes by direct-current reactive magnetron sputter. The memristive characteristics of the device were completed by time-dependent current-voltage (I-V-t) measurements, and the typical pinched hysteresis I-V loops of the memristor were observed. This paper is continued with the designing memristor emulator circuit, which has only four MOS transistors. The proposed circuit is suitable both for emulating the fabricated memristor and for using general memristor-based applications. Any circuit blocks such as a multiplier or active element are not used in the circuit to obtain memristive characteristics. All results of the proposed memristor emulator circuit are compatible with general characteristics of the fabricated semiconductor device. The MOSFET-based proposed memristor emulator circuit is laid out in the Analog Design Environment of Cadence Software using 180-nm TSMC CMOS process parameters and its layout area is 366 μm2. So as to show its performance, the dependences of the operating frequency and process corner as well as effects of radical temperature changes have been investigated in the simulation results section.
AtıfScopus94WoS77OpenAlex98İncele - MakaleYalnız künye2016Scopus SJRQ3Relationships Among some Pears Genotypes (Pyrus Communis L.) Based on ISSR and RAPD Analysis; [Bestimmung der genetischen Verwandtschaft bei Birnen mit Hilfe der ISSR und RAPD Methoden]
Kalkışım, Ozgun; Okcu, Melih; Okcu, Zuhal; Karabulut, Besim; Yildirim, Nalan; Agar, Guleray
Thirty one pears genotypes from east blacksea region were evaluated for genetic relationships by using Randomly Amplified Polymorphic DNA (RAPD) and ISSR (Inter-Simple Sequence Repeats) markers from total 70 RAPD and ISSR primer investigated, 22 could amplify clearly and consistently. Cluster analysis of the pears genotypes was performed based on data from polymorphic bands RAPD and ISSR by using Jaccard’s similarity coefficient and the Unweighted pair-group method with arithmetic average (UPGMA) clustering method. The 31 pear genotypes were classified into two major groups. Cluster A was divided into 2 subclusters: Gumushane pears and Trabzon pears. Cluster B consisted of Artvin pears. The similarity matrix values ranged between 0.105 and 0.968.
AtıfScopus10WoS8OpenAlex13İncele - BildiriAçık Erişim2018Performance and degradation analyses of two different pv modules in central anatolia
Ozden, Talat; Akinoglu, Bulent G.; Kurtz, Sarah
Ankara (latitude: around 40°N) is in Central Anatolia and the climate is dry continental. Due to the rapid transition to renewable energy policies of Turkey it is now a must to complete truthful feasibility analyses for solar power systems countrywide. Long term performance and degradation analyses have been carried out by the authors for three different arrays and many research results appearing in the literature are summarized. Present research analyzes the outdoor testing results of two PV modules monthly data. One of the modules has multi crystalline silicon (Poly-Si) cells and the other is thin film silicon (amorphous Si / microcrystalline Si tandem structure - a-Si/μc-Si) cells. The results showed that in five years the average yearly efficiency decreases from 14% to 11% for Poly-Si (14.72% is the nameplate Standard Test Condition (STC) efficiency) and from 8% to 6% for thin film modules (9.15% is STC efficiency). Our calculations are based on measured solar global-horizontal irradiance from which we calculated plane-of-array irradiation using an anisotropic sky model. We present the details of these analyses and degradation rates for the two types of modules to be used in long term feasibility analyses.
AtıfScopus11OpenAlex10İncele - MakaleYayıncıda açık erişim2018Scopus SJRQ2Finite difference method for bitsadze-samarskii type overdetermined elliptic problem with dirichlet conditions
Ashyralyyev, Charyyar; Akyuz, Gulzipa
In this paper, we apply finite difference method to Bitsadze-Samarskii type overdetermined elliptic problem with Dirichlet conditions. Stability, coercive stability inequalities for solution of the first and second order of accuracy difference schemes (ADSs) are proved. Then, established abstract results are applied to get stable difference schemes for Bitsadze-Samarskii type overdetermined elliptic multidimensional differential problems with multipoint nonlocal boundary conditions. Finally, numerical results with explanation on the realization in two dimensional and three dimensional cases are presented.
AtıfScopus10WoS7OpenAlex11İncele - BildiriAçık Erişim2018Stress Analysis and Fatigue Behaviour of PTFE-Bronze Layered Journal Bearing under Real-Time Dynamic Loading
Duman, M.S.; Kaplan, E.; Cuvalci, O.
The present paper is based on experimental studies and numerical simulations on the surface fatigue failure of the PTFE-bronze layered journal bearings under real-time loading. 'Permaglide Plain Bearings P10' type journal bearings were experimentally tested under different real time dynamic loadings by using real time journal bearing test system in our laboratory. The journal bearing consists of a PTFE-bronze layer approximately 0.32 mm thick on the steel support layer with 2.18 mm thick. Two different approaches have been considered with in experiments: (i) under real- time constant loading with varying bearing widths, (ii) under different real-time loadings at constant bearing widths. Fatigue regions, micro-crack dispersion and stress distributions occurred at the journal bearing were experimentally and theoretically investigated. The relation between fatigue region and pressure distributions were investigated by determining the circumferential pressure distribution under real-time dynamic loadings for the position of every 10° crank angles. In the theoretical part; stress and deformation distributions at the surface of the journal bearing analysed by using finite element methods to determine the relationship between stress and fatigue behaviour. As a result of this study, the maximum oil pressure and fatigue cracks were observed in the most heavily loaded regions of the bearing surface. Experimental results show that PTFE-Bronze layered journal bearings fatigue behaviour is better than the bearings include white metal alloy.
AtıfScopus4WoS5OpenAlex5İncele - MakaleYalnız künye2018Scopus SJRQ1Experimental study on cement-treated and untreated RAP blended bases: Cyclic plate loading test
Seferoğlu, Ayşegül Güneş; Seferoğlu, Mehmet Tevfik; Akpinar, Muhammet Vefa
The asphalt surrounding the reclaimed asphalt pavement (RAP) aggregates decrease the performance characteristics of road layers. RAP material increases the permanent deformation potential of road layers under the traffic load. In this study, the performances of RAP-VA (Virgin aggregate) mixtures was tested using cyclic plate loading test by adding pozzolanic cement into mixtures in order to use RAP material at the rate of 100% and to minimize the permanent deformation in plant-mix base courses (PBC). The permanent surface deformations of base course were measured at different points throughout 100 loading cycles and all of the measurements were compared to that of base course prepared from 100% VA. The effect of RAP/cement rate of mixtures on the permanent deformations was examined and it was determined that the increase in RAP rate increased the permanent deformations but cement significantly decreased it. Moreover, considering the material costs of mixtures, the cost analysis was performed and the profit margins that using RAP and cement offers to constructors were computed.
AtıfScopus24WoS22OpenAlex25İncele - MakaleAçık Erişim2017Scopus SJRQ2Synthesis of imine bond containing insoluble polymeric ligand and its transition metal complexes, structural characterization and catalytic activity on esterification reaction
Gönül, İlyas; Ay, Burak; Karaca, Serkan; Saribiyik, Oguz Yunus; Yildiz, Emel; Serin, Selahattin
In this study, synthesis of insoluble polymeric ligand (L) and its transition metal complexes [Cu(L) Cl2]·2H2O (1), [Co(L)Cl2(H2O)2] (2) and [Ni(L)Cl2(H2O)2] (3), having the azomethine groups, were synthesized by the condensation reactions of the diamines and dialdehydes. The structural properties were characterized by the analytical and spectroscopic methods using by elemental analysis, Fourier Transform Infrared, Thermo Gravimetric Analysis, Powder X-ray Diffraction, magnetic susceptibility and Inductively Coupled Plasma. The solubilities of the synthesized polymeric materials were also investigated and found as insoluble some organic and inorganic solvents. Additionally, their catalytic performance was carried out for the esterification reaction of acetic acid and butyl acetate. The highest conversion rate is 75.75% by using catalyst 1. The esterification of butanol gave butyl acetate with 100% selectivity.
AtıfScopus4WoS4OpenAlex7İncele - Derleme MakaleYalnız künye2019Scopus SJRQ4Redescription and New Record of the Harvestman Lacinius insularis Roewer, 1923 (Opiliones: Phalangiidae) from Turkey
Kurt, Kemal; Yaǧmur, Ersen Aydin
Lacinius insularis Roewer, 1923, is recorded for the first time as part of the Turkish harvestmen fauna. Prior to this, the species was only known from the island of Crete in Greece. The new collections were made on Nif mountain in İzmir Province (far western Turkey). In this study, L. insularis is redescribed based on adults from Turkey. Its detailed description, morphological characteristics, distribution and measurements are given. Also, genitalia, body dorsal view, chelicerae, and pedipalp are illustrated. In addition, this species is compared with similar species.
AtıfScopus1WoS1OpenAlex2İncele - MakaleYalnız künye2017Scopus SJRQ1Determination of optimum ejector operating pressures for anodic recirculation in SOFC systems
Genc, Omer; Toros, Serkan; Timurkutluk, Bora
In this study, a numerical analysis of an ejector for micro combined heat and power system based on 18 kW Solid Oxide Fuel Cell (SOFC) using methane as fuel is presented. An ejector design, which reflects the real system conditions in the view of the flow characteristics, is provided and the ejector performance is numerically investigated for various methane pressure to exhaust pressure ratios and methane inlet temperatures. The results show that the fuel inlet temperature and the pressure ratio of the methane to exhaust significantly affect the steam to carbon ratio (STCR) and entrainment ratio. The higher pressure ratio and methane temperature allow a high entrainment ratio and STCR, but as pressure ratio and methane temperature increase, STCR and entrainment ratio remain unchanged after a specific value. 1140 different scenarios related with the inlet and outlet pressures of the ejector and methane temperature are created to determine the optimum operating conditions. The simulations show that the optimum methane inlet pressure is 7 bar and exhaust pressure is 1.159 bar for the ejector geometry of the interest. The entrainment ratio and STCR are determined as 2.05 and 0.92, respectively at this optimum scenario.
AtıfScopus34WoS31OpenAlex37İncele - MakaleYalnız künye2019Scopus SJRQ2Effects of wood preservatives on the combustion process and combustion quality of wood
Sadiye Yasar, S.
This study examines the combustion properties of Scots pine (Pinus sylvestris L.) and Oriental beech (Fagus orientalis L.) in 3 stages (CWF, SC and EC) according to ASTM E 160-50 (1975). Wood samples were impregnated with Tanalith-E (T) and Wolmanit-CB (WC) and then were varnished with Synthetic (St) and water based (wb) varnishes. When the combustion was completed, the weight loss, combustion temperatures, illuminance values, total time of combustion, and demolition time were measured. As the result, illuminance value of Oriental beech wood decreased, while the smoke density increased. Scots pine was later destroyed in the combustion process. Areas with a risk of fire are advised to use pine wood instead of beech. Wolmanit-CB and synthetic varnish reduced the temperature and illuminance values. Oriental beech, Tanalith-E, and synthetic varnish resulted in the highest temperatures for all combustion stages. This triple interaction increased total combustion time values by more than 90% when compared with the control samples.
AtıfScopus4WoS5İncele - MakaleAçık Erişim2017Scopus SJRQ3A fourth order approximation of the neumann type overdetermined elliptic problem
Ashyralyyev, Charyyar
In this paper, we consider an inverse elliptic problem with Neumann type overdetermination and construct a fourth order of accuracy difference scheme for its solution. Stability, almost coercive stability and coercive stability estimates for the solution of difference problem are proved. Later, we construct a fourth order difference scheme for an inverse problem for multidimensional elliptic equation with Neumann type overdetermination and Dirichlet boundary condition. Finally, we illustrate numerical example with descriptions of numeric realization in a two-dimensional case.
AtıfScopus19WoS12OpenAlex17İncele
