2017 Cilt 22 Sayı 3

Permanent URI for this collectionhttps://hdl.handle.net/11452/12075

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Comparison of some phenolic compounds of organic and conventional extra-virgin olive oil
(Uludağ Üniversitesi, 2017-12-01) Çelik, Güler; Doğangün, Esra; Şahan, Yasemin; Uludağ Üniversitesi/Mühendislik Fakültesi/Gıda Mühendisliği Bölümü.
Olive oil is an important ingredient of the Mediterranean diet, because of its nutritional qualities and organoleptic characteristics. In addition olive oil has positive effects on human health, in particular to prevent of some types of cancer and cardiovascular diseases and as regards diabetes, inflammatory and autoimmune diseases. These properties are related not only to the fatty acid composition of its lipid matrix, but especially to the presence of the phenolic compounds. The changes in the phenolic compounds of EVOO can be an important quality control parameter. The aim of this study was to determine the changes in the some phenolic compounds of organic and conventional extra-virgin olive oil (EVOO) from Turkey. Five phenolic compounds oleuropein, hydroxytyrosol, tyrosol, caffeic acid, p-coumaric acid were quantified LC-DAD and justified by LC-MS. Ten extra virgin olive oils (organic and conventional extra-virgin olive oil), produced by different brands were analyzed. Oleuropein were found to be higher than other phenolic compounds. The amount decreased with the order of tyrosol, hydroxytyrosol, caffeic acid, p-coumaric acid, respectively. Oleuropein concentration varied between 3.8- 39 mg/kg in organic production of extra virgin olive oils. As a conclusion, phenolic content are higher in organic products compared to conventional products of EVOO.
Determination of void fraction by image processing
(Uludağ Üniversitesi, 2017-09-28) Dibek, Burak; Demir, Hakan
Void fraction is one of the key parameters for defining the characteristics of a two phase flow. However, determination of void fraction is not easy due to changing conditions of flow and the type of fluid. In literature, there are plenty of works on determination of void fraction in two-phase flow in a pipe or channel which uses psychical parameters and properties of the system, flow and fluid. Since there are plenty number of correlations for various flow types, an experimental method has been suggested to determine the void fraction according to flow type without using any physical parameter of the flow and fluid. Image visualization methods have been applied to two-phase flow of refrigerant R600a in a circular tube. The images from high speed photography have been processed using a software developed with MATLAB Image Processing Toolbox. The results were also compared with the well-known correlations.
Determination the number of ants used in aco algorithm via grillage optimization
(Uludağ Üniversitesi, 2017-12-27) Aydın, Zekeriya
Ant colony optimization (ACO) algorithm is one of the artificial intelligence methods used in structural optimization. Values of some optimization parameters must be determined before the optimization process in most of the artificial intelligence based optimization algorithms. Determination of the values of these optimization parameters is essential especially for the time required for the optimization process and the quality of results achieved. Pheromone update coefficient, number of ants in the colony, number of depositing ants, penalty coefficient are the main optimization parameters in ACO algorithm. This study is focused on the number of ants in the ant colony. This research is realized using the optimization of grillage structure which is one of the well-known optimization problems in the literature. Minimization of the weight of structure is the objective function of the optimization problem, and the member sizes of grillages are considered as discrete design variables. Displacement and strength restrictions are considered as constraints according to manual of LRFD-AISC. A computer program is coded in BASIC to accomplish the structural design and optimization procedures. Numerical examples from literature are optimized using different number of ants to determine the effect of the number of ants on the optimization process. At the end of the study, some inferences are presented on the number of ants to be used in the colony.
Impedance spectroscopy and dielectric relaxation in phthalocyanine thin film
(Uludağ Üniversitesi, 2017-10-16) Can, Nursel; Altındal, Ahmet
Dielectric relaxation behavior of spin coated thin film of novel ball-type binuclear zinc(II) phthalocyanine were studied using impedance spectroscopy technique over a frequency range of 5– 13x106 Hz and temperatures (298 – 468 K). Simulation of the obtained impedance data indicated that the dielectric behaviour of the system can be modeled by a parallel RC electrical equivalent circuit. A frequency dependence in the form of ω m , where the index m is found strongly temperature dependent, was observed for the ac conductivity σac. Ac conductivity data were analyzed in terms two different models. The observed temperature dependence of the m indicate that the ac charge transport in Pc film take place via hopping process.
Investigation of the effect of the roof geometry on building thermal behaviour
(Uludağ Üniversitesi, 2017-12-05) Yıldırım, Erdal; Fıratoğlu, Zeynel Abidin; Yeşilata, Bülent
Main objective of this study is to investigate effect of the roof geometry on indoor air conditions in terms of energy efficiency in summer. Harran’s conical roofed building has for this purpose been compared with flat roofed building of equivalent thermo-physical properties, base area and volume. Three dimensional CFD simulations using the low-Reynolds number modeling (LRNM) and standard turbulence models are performed. The effect of roof geometry on natural ventilation is investigated. Cross ventilation flow rates and convection heat transfer coefficients for these two roof types are evaluated for this purpose. Cross ventilation flow rate for the house with conical roof is found to be 8% higher than that of the flat one. The result of the numerical analysis reveals as well that the conical roof transfers 30% less heat to interior side for a representative summer day, resulting in lower indoor air temperature in the house.
Parametric vs. non-parametric efficiency assessment: Case of power plants in Turkey
(Uludağ Üniversitesi, 2017-09-21) Sarıca, Kemal
Throughout the study, the operational and long term investment performances of various power plants in Turkey are assessed and compared using Stochastic Frontier Analysis (SFA) and Data Envelopment Analysis (DEA). The data set is composed of 65 thermal, hydro and wind power plants with private and public ownership. Efficiency indices, reflecting operational and investment performance, are described and elaborated. Returns to scale, (constant and variable), assurance region, slack based measure, system comparison and bilateral type DEA models as well as stochastic frontier analysis employing the Cobb-Douglas and Translog production functions are used in the analysis. An analysis of returns to scale is carried out. The properties of the production frontiers are described for all efficiency indices. Public-private sector plants, renewable-thermal plants as well as natural gas-coal versus oil fired plants are compared according to their efficiency performance values. Efficiency scores obtained from DEA and SFA are compared and some relationships are identified. Interesting relationship are identified by elaborating the efficiency indices and various input/output factors. Even though natural gas fired power plants outperforms the coal fired ones in terms of investment efficiency, in general, reverse is true for operational performance under variable returns to scale.
Real time trajectory tracking of moving objects using adaptive fuzzy time series and exponential smoothing forecasting techniques
(Uludağ Üniversitesi, 2017-09-21) Yağımlı, Mustafa
In his study; in cases where the targeted object which is taken from a real time camera shot is in a circular motion, quasi projectile motion and maneuvering dynamic motion, its later location where it will be is examined using the Adaptive Fuzzy Time Series (AFTS) and Exponential Smoothing (ES) estimation methods. Error evaluation of these motions was performed according to the Mean Absolute Percentage Error (MAPE) method. In the conducted evaluation, with AFTS, the circular motion was found to be 3.65%, quasi projectile motion 9.12%, and maneuvering dynamic motion 19.23%, and with ES, circular motion 4.48%, quasi projectile motion 1.13% and maneuvering dynamic motion was found to be 0.61%. AFTS gives better results than ES for the circular motion but ES gives better results than AFTS for quasi projectile and maneuvering dynamic motions.

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