Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
Browse
4 results
Search Results
Article Citation - WoS: 10Citation - Scopus: 10Constructal Microdevice Manifold Design With Uniform Flow Rate Distribution by Consideration of the Tree-Branching Rule of Leonardo Da Vinci and Hess-Murray Rule(The American Society of Mechanical Engineers(ASME), 2017) Çetkin, ErdalIn this paper, we show how the design of a microdevice manifold should be tapered for uniform flow rate distribution. The designs based on the tree-branching rule of Leonardo da Vinci and the Hess-Murray rule were considered in addition to the constructal design. Both da Vinci and Hess-Murray designs are insensitive to the inlet velocity, and they provide better flow uniformity than the base (not tapered) design. However, the results of this paper uncover that not only pressure drop but also velocity distribution in the microdevice play an integral role in the flow uniformity. Therefore, an iterative approach was adopted with five degrees-of-freedom (inclined wall positions) and one constraint (constant distribution channel thickness) in order to uncover the constructal design which conforms the uniform flow rate distribution. In addition, the effect of slenderness of the microchannels (Svelteness) and inlet velocity on the flow rate distribution to the microchannels has been documented. This paper also uncovers that the design of a manifold should be designed with not only the consideration of pressure distribution but also dynamic pressure distribution especially for non-Svelte microdevices.Article Citation - WoS: 2Citation - Scopus: 2Soft Computing and Regression Modelling Approaches for Link-Capacity Functions(Czech Technical University in Prague, 2016) Koşun, Çağlar; Tayfur, Gökmen; Çelik, Hüseyin MuratLink-capacity functions are the relationships between the fundamental traffic variables like travel time and the flow rate. These relationships are important inputs to the capacity-restrained traffic assignment models. This study investigates the prediction of travel time as a function of several variables V/C (flow rate/capacity), retail activity, parking, number of bus stops and link type. For this purpose, the necessary data collected in Izmir, Turkey are employed by Artificial Neural Networks (ANNs) and Regression-based models of multiple linear regression (MLR) and multiple non-linear regression (MNLR). In ANNs modelling, 70% of the whole dataset is randomly selected for the training, whereas the rest is utilized in testing the model. Similarly, the same training dataset is employed in obtaining the optimal values of the coefficients of the regression-based models. Although all of the variables are used in the input vector of the models to predict the travel time, the most significant independent variables are found to be V/C and retail activity. By considering these two significant input variables, ANNs predicted the travel time with the correlation coefficient R = 0:87 while this value was almost 0.60 for the regression-based models.Article Citation - WoS: 22Citation - Scopus: 33Uv-C Irradiation of Freshly Squeezed Grape Juice and Modeling Inactivation Kinetics(John Wiley and Sons Inc., 2014) Ünlütürk, Sevcan; Atılgan, Mehmet ReşatUV inactivation kinetics of freshly squeezed turbid white grape juice (FSTGJ) treated with an annular flow UV reactor by applying UV dosages ranging from 0 to 116.7J/mL, at three different flow rates (0.90, 1.75 and 3.70mL/s), were modeled by using log-linear, Weibull, Hom and modified Chick-Watson models. FSTGJ was circulated five times in the UV system, i.e., UV exposure time was 20.33min during processing. The populations of Escherichia coli K-12, lactic acid bacteria (LAB) and foodborne yeasts were reduced by 3.759, 4.133 and 1.604log cfu/mL, respectively, after exposure to UV dosage of 116.7J/mL at the lowest flow rate. The inactivation kinetics of foodborne yeasts were best described by the modified Chick-Watson model, with the least root mean squared error (RMSE=0.001, R2=0.999). Besides, the inactivation kinetics of E.coli K-12 and LAB were best fitted by Weibull model (R2=0.999). Additionally, when the UV exposure time was increased up to 32.5min (i.e., eight cycles), UV-C treatment of FSTGJ resulted in 5.341log cfu/mL reduction in E.coli K-12, which meets the Food and Drug Administration requirement of a 5log reduction of microorganisms in fruit juices. Practical Applications Consumer demand for high-quality fruit juice with fresh-like characteristics has markedly expanded in recent years. UV-C irradiation is a nonthermal method and allows the processing of fruit juices with a minimal or no changes in flavor, essential nutrients and vitamins. Although thermal pasteurization is the most convenient way of increasing the shelf life of fruit juices, it causes a "cook taste" in grape juice. So, in this study, the application of UV-C irradiation to process grape juice was investigated. The shape of the microbial inactivation curve is sigmoidal in UV treatment. Therefore, different kinetic models (e.g., log-linear, Weibull, Hom and modified Chick-Watson) are applied to describe the inactivation kinetics of Escherichia coli K-12, lactic acid bacteria and foodborne yeasts. Kinetic parameters (e.g., k and D) and models can be used for the development of UV-C irradiation process to ensure microbial safety in juice products.Article Citation - WoS: 10Citation - Scopus: 11Use of Clinoptilolite in Ethanol Dehydration(Taylor and Francis Ltd., 1996) Tıhmınlıoğlu, Funda; Ülkü, SemraClinoptilolite-type natural zeolite, which exists in various regions of Turkey, has been experimentally studied. For the ethanol-water-local clinoptilolite system, uptake and breakthrough curves were determined under a nitrogen gas atmosphere. In adsorption kinetics and adsorption equilibrium studies, the effects of particle size, temperature and, amount of zeolite on the uptake rate have been investigated. The breakthrough curves for four different flow rates of ethanol and three different bed heights were determined in dynamic column studies. The results of the experiments show that intraparticle diffusion is the main resistance. The local clinoptilolite is a promising adsorbent for water adsorption from aqueous ethanol.