Yayınlar
Koleksiyondaki öğeler
- BildiriAçık Erişim2010The effect of PowerPoint presentations prepared and presented by prospective teachers on biology achievement and attitudes toward biology
Gürbüz, Hasan; Kişoǧlu, Mustafa; Erkol, Mehmet; Alaş, Ali; Kahraman, Sakip
The study aims to explore the effect of preparing and presenting powerpoint slides on prospective teachers' biology achievement and attitudes toward biology. The sample of the study was 109 freshman students from Pre-School Education Department at Atatürk University in Turkey. The sample was randomly assigned as control group consisted of 53 students and experimental group consisted of 56 students. The experimental group was taught by powerpoint presentations preparing and presenting by prospective teachers while the lesson was conducted through traditional approach in the control group. Results indicated that preparing and presenting powerpoint slides had a significant effect on prospective teachers biology achievement and attitudes towards biology.
AtıfScopus5WoS8OpenAlex19
İncele - MakaleYalnız künye2012Scopus SJRQ1A nondestructive testing technique: Nail penetration test
Selcuk, Levent; Gökce, H. Suleyman; Kayabali, Kamil; Simsek, Osman
This study presents a practical nondestructive testing (NDT) method: the nail penetration test (NPT). The major tools of the test technique are a gas nailer with 130 J (95.88 ft-lbf) power, concrete nails, and a gas nailer cell. The study covers three different limestone aggregate types. Six concrete mixtures were prepared from each aggregate type. Five nail shots were performed on each concrete mixture (or grade) and the average value was obtained. The average nail penetration depths were correlated with the compressive strength of concrete. Other NDT techniques, such as the Schmidt rebound hammer (SRH), ultrasonic pulse velocity (UPV), and Windsor probe (WP), were also applied to concrete samples. The measured compressive strength values were compared with those obtained from the empirical relationships using the data from the NPT, SRH, UPV, and WP. It was found that the reliability of the NPT to estimate the compressive strength of concrete is very high. The tool employed in the investigation covers a relatively wide range of compressive strength of concrete. This testing tool is proposed to estimate the compressive strength of in-place concrete.
AtıfScopus15İncele - MakaleAçık Erişim2011Scopus SJRQ3Purification and characterization of a pectin lyase produced by Geobacillus stearothermophilus Ah22 and its application in fruit juice production
Demir, Nazan; Nadaroglu, Hayrunnisa; Tasgin, Esen; Adiguzel, Ahmet; Gulluce, Medine
Extracellular pectin lyase (PL) (EC 4.2.2.10) was produced by Geobacillus stearothermophilus Ah22 in solid state fermentation. The PL enzyme was purified 40.8-fold by DEAE-cellulose anion exchange column chromatography and characterized. The molecular weight of the enzyme was determined as 36 kDa by Sephadex G-100 gel filtration chromatography. Purification of the enzymewas verified by SDS-PAGE. The optimumpHand temperature of the enzyme were determined as pH 6.0 and 60°C, respectively. The PL was mostly stable at 40°C. Its activity deceased by 50% after 2 h at 60°C and by 60% after 6 h at 50°C. The V max and K m were calculated as 0.47 mg/mL and 355.3 μmol/L•min, respectively. The presence of 10 mM Ca 2+, Cu 2+, Mn 2+, Mg 2+, Zn 2+, Hg 2+, Fe 2+ and EDTA, L-cysteine and ascorbic acid significantly enhanced enzyme activity. The purified PL enzyme was used in the production of fruit juices; yields of fruits juice improved significantly compared with controls.
AtıfScopus35WoS28OpenAlex28İncele - MakaleAçık Erişim2012Scopus SJRQ3Dynamic and interactive mathematics learning environments: The case of teaching the limit concept
Martinovic, Dragana; Karadag, Zekeriya
This theoretical study is an attempt to explore the potential of the dynamic and interactive mathematics learning environments (DIMLE) in relation to the technological pedagogical content knowledge (TPACK) framework. DIMLE are developed with intent to support learning mathematics through free exploration in a less constrained environment. A typical DIMLE software package has interactivity and dynamism as key affordances; these are especially suitable for enhancing learning and teaching with technology of the essentially dynamic mathematics concepts. Moreover, we propose that DIMLE and their affordances should be studied under the TPACK framework because this framework is explicit in considering technology-supported mathematics learning as a qualitative add-on as contrasted to what would be a simple totalling of technological, pedagogical and mathematical knowledge. As an example, we focus in our discussion on using a DIMLE in order to support learner in development of the limit concept.
AtıfScopus15OpenAlex29İncele - BildiriYalnız künye2014Application of S-UTD-CH model into multiple diffraction scenarios at 900MHz
Tabakcioglu, Mehmet Baris; Ayberkin, Doruk
In this study, propagation prediction models based on ray tracing in coverage estimation for broadcasting systems are compared with respect to computation time and accuracy. Uniform Theory of Diffraction (UTD), Slope Diffraction (S-UTD) and Slope UTD with Convex Hull (S-UTD-CH) models are compared for computation time and propagation path loss. Moreover in this study, effects of transmitter height to relative path loss at the receiver are analyzed. S-UTD-CH model is optimum model with respect to computation time and relative path loss.
- MakaleYalnız künye2019Scopus SJRQ2Heat transfer enhancement in cylindrical fins through longitudinal parabolic perforations
Cuce, Erdem; Oztekin, Erman Kadir; Cuce, Pinar Mert
In our previous works, it is clearly addressed that optimisation of fin profile is of vital importance in terms of the rate of heat transfer from a hot surface, and the optimisation procedure depends on several factors. Within the scope of this research, a longitudinal cylindrical fin profile is under interest for the optimisation research. The purpose is to investigate the effects of longitudinal parabolic perforations on the fin parameters such as temperature distribution, effectiveness and efficiency, in which the fin surface is cooled by natural convection and radiation. Different concavity levels are considered to form parabolic perforations. The rate of heat transfer from fin surface is numerically correlated with the fin mass with respect to different concavity levels. According to results, heat transfer from unit fin mass is enhanced with the new designs. The outcome of the study can be used to optimise the needs for particular applications by making a decision between heat loss and weight options. That is, the increase in the concavity level of the perforation results in a lighter and cheaper design, but yielding a lower heat loss. However, heat transfer from unit mass is still enhanced.
AtıfScopus4WoS5OpenAlex9İncele - MakaleAçık Erişim2014Scopus SJRQ2Assessment of kinetics, thermodynamics, and equilibrium parameters of Cu(II) adsorption onto Rosa canina seeds
Serencam, Huseyin; Ozdes, Duygu; Duran, Celal; Senturk, Hasan Basri
Rosa canina seeds (RCS) is considered as a low-cost and promising adsorbent in removal of metal ions; hence, in the present study, we aimed to test the adsorptive removal of Cu(II) ions from aqueous solutions by utilizing RCS in a batch process. After characterization of RCS by using several techniques, the effects of various experimental parameters such as initial pH of aqueous solution, contact time, initial Cu(II) concentration, RCS concentration, temperature, and electrolyte concentration were studied upon the adsorption process. The desorption conditions of Cu(II) ions from the loaded RCS were also evaluated. Maximum Cu(II) adsorption was found to occur at pH 6.0 and the equilibrium was established after 60 min of contact time. The adsorption isotherms were described by means of Langmuir, Freundlich, Temkin, and Dubinin Radushkevich models. The adsorption kinetics were analyzed using pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion models and the adsorption data were well described by the pseudo-second-order model. Thermodynamic parameters such as the Gibbs free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) changes were also evaluated and it has been found that the adsorption process was feasible, spontaneous, and endothermic in the temperature range of 278-313 K.
AtıfScopus19WoS20OpenAlex19İncele - MakaleYalnız künye2016Scopus SJRQ3Thermodynamic optimization of a zero CO2 emission cogeneration cycle
Karaali, Rabi; Ozturk, Ilhan Tekin
CO2 emissions that have the greatest negative impact on the greenhouse and the global warming that should be decreased or kept at the same rates. Today fossil fuels share 60 % of total electricity production of the world, which plays an important role on CO2 emissions. Thermal cogeneration and zero CO2 emission cycles have potential for reducing this effect. By taking into consideration the most applicable and important zero CO2 emission cycles, a new cycle is designed. Thermodynamic analyses and optimization of this cycle is studied with FORTRAN code. The optimization results of this cycle show that the maximum exergy efficiency of this new cycle is 64 %, which is 17.6 % higher than (0,544) the one for the air preheated cogeneration cycle (APHCC) and 18.7 % higher than (53,9) the absorption cooling zero CO2 emission cycle (ACZEC). In the introduced new cycle, steam and CO2 in the exhaust gases are condensed so that the condensing energy of them is regained. For that reason, the heat output and the electrical power of the introduced cycle is better than the other cogeneration cycles.
AtıfScopus3İncele - MakaleAçık Erişim2017Scopus SJRQ3Enhanced Pinning Properties of Laser-Irradiated Bulk MgB2 Superconductors
Erdem, O.; Yanmaz, E.
In order to investigate the effect of laser irradiation on the superconducting properties of MgB2, a pellet-shaped sample was produced and cut into two pieces. The dot-shaped molten patterns, with the distance of 100 µm between them, were formed on the surface of one of the pieces by using an Nd:YVO4 laser. The grains of the irradiated sample were significantly grown due to the laser-induced sintering. The modified surface appeared to have dense and compacted grains as a result of increasing interconnectivity among the superconducting grains. The critical current densities at 5 K in a field of 3 T were found to be 5.38 × 104 and 8.96 × 104 A cm−2 for the reference and the irradiated samples, respectively. The increment of critical current density for the irradiated sample is presumably connected with the changing of pinning mechanism after the laser irradiation. For the irradiated sample which showed a higher value of critical current density at 5 K under high fields, Δκ pinning was obtained as a dominant pinning mechanism, while the normal point pinning was dominant for the reference one. These results point out that the superconducting properties of bulk MgB2 can be changed and improved via laser irradiation in a short time.
AtıfScopus12WoS10OpenAlex11İncele - MakaleAçık Erişim2013Scopus SJRQ1Effect of ultrasonic treatment on reduction of Esherichia coli ATCC 25922 and egg quality parameters in experimentally contaminated hens' shell eggs
Sert, Durmus; Aygun, Ali; Torlak, Emrah; Mercan, Emin
Backround: In this study, hen eggs which were experimentally contaminated with Esherichia coli ATCC 25922 were used. Contaminated eggs were washed statically (S5 to S30; 0 kHz) and by ultrasonic waves (U5 to U30; 35 kHz) for given applications of time (5, 15 and 30 min), then the eggs were stored at 22°C for 14 days. Results: Depending on the time of ultrasonic application, a significant increase in egg shell strength (P < 0.01) was recorded. The highest value of the Haugh unit (67.93, 1 day) was observed on the eggs which were washed by ultrasonic waves. Yolk width values of ultrasonic washed eggs diminished. E. coli was completely removed by 30 min of ultrasonic application. During storage E. coli growth was not detected on the eggs which were washed by ultrasonic waves except the eggs in U5 group (2.04 log CFU eggshell-1) on the first day of storage. Conclusion: Depending on the time of ultrasonic application a significant increase in egg quality parameters (shell strength, albumen height, Haugh units, and yolk height) were observed. The application of ultrasound led to a significant reduction in E. coli numbers on egg shells.
AtıfScopus21WoS20OpenAlex21
İncele - BildiriYalnız künye2017Multi-manned assembly line balancing problem: Resource constrained case
Yilmaz, Hamid; Yilmaz, Mustafa
In this paper, a new approach on multi-manned assembly line balancing problem is presented. The goal of proposed approach is to establish balance of multi-manned assembly line with minimum number of worker, workstation and resources. For this purpose, mathematical model is developed for the problem. Finally, this model is solved for a numerical example using Gurobi to indicate the applicability of the proposed mathematical model.
AtıfScopus1İncele - MakaleAçık Erişim2019Scopus SJRQ1High temperature resistance of boron active belite cement mortars containing fly ash
Gökçe, H.Süleyman
Boron allowing stability of reactive belite phase in clinker production enhances neutron shielding capability of cement. In the study, neutron attenuation factor of boron active belite cements at various fly ash introduction was theoretically revealed by comparing with an alternative low heat cement (portland composite cement). High temperature resistance of the cements with and without fly ash introduction was determined on standard mortar prisms at elevated temperatures up to 900 °C with regard to compressive strength and flexural strength. Neutron shielding performance of boron active belite cement was found almost 25 times higher than Portland composite cement. Fly ash introduction significantly reduced the neutron attenuation factor of boron active belite cement. High temperature resistance of boron active belite cement mortar was found lower than that of Portland composite cement mortar at 700 °C at later curing time. 10% fly ash introduction improved the high temperature performance of boron active belite cement mortar exposed to 900 °C. Residual compressive strength values of the mortars containing fly ash were between 16% and 28% after exposing 900 °C.
AtıfScopus39WoS36OpenAlex39İncele - MakaleAçık Erişim2018Scopus SJRQ1Thermoeconomic multi-objective optimization of an organic Rankine cycle (ORC) adapted to an existing solid waste power plant
Özahi, Emrah; Tozlu, Alperen; Abuşoğlu, Ayşegül
In this paper, thermodynamic and thermoeconomic analyses, and also optimization of an organic Rankine cycle (ORC) were performed. The system was adapted to an existing solid waste power plant with a 5.66 MW installed power capacity in order to produce additional power from the exhaust gas. The actual operating data of the plant were utilized during all stages of the analyses. The originality of this paper is based on the analysis of the possibility of the energy conversion of an exhaust gas with a temperature of 566 & #x000B0;C into the electricity by utilizing an ORC system in the concept of waste-to-energy. Four different working fluids: toluene, octamethyltrisiloxane (MDM), octamethyl cyclotetrasiloxane (D4) and n-decane were considered and analyzed for the current system. This is also another novelty of this study due to lack of such a study, in the open literature, that deals with an ORC utilized for a typical municipal solid waste power plant. According to the thermoeconomic analyses, toluene was found to be the optimum working fluid with the maximum power output of 584.6 kW and the exergy efficiency of 15.69%. The optimization of the cycle was performed by using the non-dominated sorting genetic algorithm method (NSGA-II) in MATLAB software environment. The optimization results were compared and the deviations of the net power output and the total cost rate were evaluated as & #x2212;5.89%, & #x2212;3.51 & #x00024;/h for toluene; 0.96%, & #x2212;3.60 & #x00024;/h for MDM; 8.45%, & #x2212;2.04 & #x00024;/h for D4 and 2.00%, & #x2212;5.54 & #x00024;/h for n-decane, respectively.
AtıfScopus87WoS80OpenAlex88İncele - MakaleAçık Erişim2015Scopus SJRQ3An investigation of self-image congruence differences between materialistic and non-materialistic consumers
Başar, Enes Emre; Türk, Bahar; Ünal, Sevtap
This research aims to determine whether there are differences in the self-image congruence between materialistic and non-materialistic consumers towards different product categories (social and private consumption products). The study was carried out on the students of Erzurum Ataturk University using the survey method. Results indicate that there are significant differences in the self-image congruence between materialistic and non-materialistic consumers. Additionally, non-materialistic consumers choose products that reflect their actual selves, whereas materialistic consumers choose products that support their ideal selves.
AtıfScopus4OpenAlex6İncele - MakaleAçık Erişim2019Scopus SJRQ2Resource- and content-aware, scalable stitching framework for remote sensing images
Eken, Süleyman; Mert, Ümit; Koşunalp, Selahattin; Sayar, Ahmet
This paper proposes a new approach to solving the scalability problem in stitching and registration of satellite images. The image stitching process is mostly utilized to capture an image of an entire object, whose parts fall in separate but overlapping mosaics. Due to their high resolutions and huge sizes, the stitching of satellite mosaic images is time- and resource-consuming process. The work presented in this paper proposes a resource- and content-aware, scalable stitching technique. The main idea is based on measuring and assessing the available hardware resources of the machine, on which stitching process runs, and scaling the resolution of the images accordingly. Moreover, preprocessing is not needed, and the adjustment is performed dynamically at run time. The effectiveness of the proposed technique was assessed by partially registering overlapping satellite mosaic images of the island of Cyprus and Lake Van. The scalability tests are performed on varying numbers and sizes of the overlapping LandSat-8 satellite images.
AtıfScopus8WoS6OpenAlex8İncele - MakaleAçık Erişim2017Scopus SJRQ3Comparison of wintering ability and colony performances of different honeybee (Apis mellifera L.) genotypes in eastern Anatolian/turkey conditions; [Doğu anadolu-Türkiye koşullarinda farklı bal arısı (Apis mellifera L.) genotiplerinin kışlama yeteneği ve koloni performanslarinin karşılaştırılması]
Cengiz, Mahir Murat; Erdoğan, Yaşar
In this study, wintering ability and some physiological properties of Buckfast, Carniolan, Caucasian and Erzurum honeybee genotypes were investigated in Eastern Anatolian conditions. During the wintering season of 2014, a total of 48 colonies, 12 from each of Buckfast, Carniolan, Caucasian and Erzurum honey bee genotypes, were taken from the equilibrated colonies of Langstroth type wooden hives for wintering. In the 2015 production period, a total of 43 colonies,11 from each of Buckfast, Carniolan, Erzurum genotypes and 10 from Caucasian genotype were used in the study. In the production season, the average number of combs covered with bees in genotype groups were found as 11.72±0.63, 12.17±0.62, 9.52±0.51 and 10.72±0.55 per colony, and the average brood areas were found as 2713.7±237.9, 2797.6±238.3, 2036.5±166.4, 2364.3±197.2 cm2/colony (19.04.2015-4.10.2015). The difference between the groups was found statistically significant (P<0.01) in terms of number of combs covered with bees and brood areas. Averarage honey yields were determined as 28.08±2.37, 29.94±2.17, 19.28±2.13 and 23.36±2.15 kg/colony, respectively. The difference between groups in honey yield was found statistically significant (P<0.05).
AtıfScopus9WoS5OpenAlex8İncele - MakaleAçık Erişim2019Scopus SJRQ2Fruit and seed macro- and micromorphologies of the genus Matthiola (Brassicaceae) in turkey and their taxonomic value
Kaya, Ayla; Ünal, Murat; Sefali, Abdurrahman; Martin, Esra
Macro- and micromorphological features of fruit and seeds belonging to 12 taxa genera of Matthiola W.T.Aiton were studied via stereomicroscope and scanning electron microscope. In macromorphological studies, the following variables were investigated: The shape, size, and color of fruit and seeds; the length of fruiting pedicel; the structure of the median vein; stigma (horns); and trichome properties and density in fruit. In micromorphological studies, the presence or absence of seed wings, seed coat pattern in disc and wing, and epidermal cell shape in disc and wing were determined. According to our findings, all characters of fruit and seeds are extremely variable and can be used as criteria to distinguish species of the genus.
AtıfScopus5WoS4TR Dizin1
İncele - MakaleAçık Erişim2018Learning styles as the predictor of academic success of the pre-service history teachers
Elban, Mehmet
In this study, the relations between learning styles and academic success of pre-service history teachers were examined. The study group of this research was comprised of 142 pre-service history teachers, who attended Bayburt University, Faculty of Humanities and Social Sciences, Department of History in spring quarter of 2017-2018 academic year. "Grasha-Reichmann Learning Style Scale" was used in collection of data for the research. As per the academic success of the pre-service history teachers, averages of their four major area course grades were recorded. In the analysis of the research data, descriptive statistics, t-test for the independent groups, and multiple regression analysis were used. It was understood that the dominant learning styles of pre-service history teachers were, respectively, dependent, independent, participant, collaborator, avoidant, and competitive learning styles. Also, it was found that gender variable has not significant effect on pre-service history teachers’ learning style. In the regression analysis, it was discovered that the learning styles of pre-service history teachers are predictive for their academic success. Moreover, it was understood that only participant and competitive learning styles significantly predicted the academic success. In other words, learning styles of pre-service history teachers accounted for 28 % of academic success of the pre-service history teachers.
AtıfScopus6OpenAlex21İncele - MakaleAçık Erişim2016Scopus SJRQ1Experimental determination of Drucker-Prager yield criterion parameters for normal and high strength concretes under triaxial compression
Öztekin, Ertekin; Pul, Selim; Hüsem, Metin
In this study, parameters which define Drucker-Prager yield criterion were investigated experimentally for both normal strength concrete (NSC) and high strength concrete (HSC) by triaxial compression tests. Total 16 concrete series with different concrete strength were produced. While 8 concrete series were produced as NSC (20 MPa < fcm < 55 MPa), other 8 series were produced as HSC (55 MPa < fcm < 85 MPa). Each series contains 16 specimens. Triaxial compression tests were performed on these concrete specimens. Concrete compressive strength of the specimens were measured under 4 different lateral compression level (0, 1, 2 and 4 MPa). After Mohr circles were drawn by using the data obtained from triaxial compression tests, the values of cohesion were determined between 5 MPa and 13 MPa for NSC and 13 MPa and 19 MPa for HSC. The values of internal friction angle were also obtained between 27° and 34° for NSC, 34° and 39° for HSC from the Mohr circles. The parameters defining the Drucker-Prager yield criterion were determined by using the values of cohesion and internal friction angle. Finally, after some equations were proposed to calculate the parameters by using concrete compressive strength, the validation of these equations were also proved in this study.
AtıfScopus83WoS74İncele - MakaleYalnız künye2017Scopus SJRQ1Microbial diversity of traditional kefir grains and their role on kefir aroma
Dertli, Enes; Çon, Ahmet Hilmi
Kefir grains consist of rich bacterial and fungal microflora responsible for the production of this traditional fermented milk beverage with unique flavour properties. Here, a pyrosequencing approach was applied for the identification of microbial flora of four kefir grains collected from different regions of Turkey and the volatile compounds in kefir samples produced with these grains were determined. Lactobacillus kefiranofaciens presented in all grains at important levels and Enterobacter, Acinetobacter, Enterococcus and Pseudomonas spp. were observed in traditional kefir grains. The fungal microflora of kefir grains was dominated by yeast species and Dipodascaceae family was dominant and Saccharomyces cerevisiae presented in all grains. Other yeast species belonging to Kazachstania, Candida, Issatchenkia and Rhodotorula species were also detected in kefir grains. Volatile compounds of kefir samples were also diverse related to the microbial diversity of kefir grains. This study revealed the rich microflora of Turkish kefir grains and their interactions with the aromatic properties of kefir.
AtıfScopus143WoS130OpenAlex174İncele
