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Öğe An experimental investigation of the effect of thermophysical properties on time lag and decrement factor for building elements(Gazi University, 2020-06-01) Oktay, Hasan; Yumrutaş, Recep; Argunhan, ZekiThe time lag (TL) and decrement factor (DF) are essential for the heat storage capabilities of building elements, which strictly depend on the thermophysical properties of the elements. Many investigations are presented in literature arguing to find the influence of each thermophysical property on TL and DF by keeping the other properties constant. This study aims to investigate the effect of each property on TL and DF, utilizing relationships between the measurement values of the thermophysical properties of wall materials. Therefore, first, 132 new concrete wall samples were produced, and their thermophysical properties were tested. Secondly, TL and DF values for each building element are computed from the solution of the problem by Complex Finite Fourier Transform (CFFT) technique. Finally, a multivariate regression analysis has been performed, and the variations of each thermophysical property versus TL and DF are presented, and also the findings are compared with literature. The results show that each property alone (keeping the other properties constant) is not adequate to identify the thermal inertia and thermal performance of a wall element. Besides, 87.3 % decrease in thermal diffusivity corresponds to 6.03 h increase in the value of TL and 88.8 % decrease in value of DF; respectively, for W1 wall assembly.Öğe Docking and molecular dynamics calculations of some previously studied and newly designed ligands to catalytic core domain of HIV-1 integrase and an investigation to effects of conformational changes of protein on docking results(Türkiye Kimya Derneği, 2017-01-09) Ercan, SelamiNowadays, AIDS still remains as a worldwide pandemic and continues to cause many deaths which arise from HIV-1 virus. For nearly 35 years, drugs that target various steps of virus life cycle have been developed. HIV-1 integrase constitutes one of these steps which is essential for virus life cycle. Computer-aided drug design is being used in many drug development and drug improvement studies as also used in development of the first HIV-1 integrase inhibitor Raltegravir. In this study, 3 ligands which are already used as HIV-1 integrase inhibitors and 4 newly designed ligands were docked to catalytic core domain of HIV-1 integrase. Each ligand docked to three different conformations of protein. Prepared complexes (21 items) were carried out by 50 ns MD simulations and results were analyzed. Finally, the binding free energies of ligands were calculated. It was determined that designed ligands L01 and L03 gave favorable results. The questions about the ligands which have low docking scores in a conformation of protein could give better scores in another conformation of protein and if the MD simulations carry the different oriented and different localized ligands in same position at the end of simulation were answered.Öğe Performance and exhaust emissions of a DI diesel engine fueled with waste cooking oil and inedible animal tallow methyl esters(TÜBİTAK, 2011) Altun, ŞehmusThe performance and exhaust emissions of a direct injection diesel engine were experimentally investigated using 2 biodiesel fuels with promising economic perspective, one obtained from inedible animal tallow and the other from waste cooking oils. Inedible animal tallow, which is obtained from a mixture of slaughtered cattle and sheep fats collected from a local slaughterhouse during meat preparation process, was transesterified using methyl alcohol and an alkaline catalyst to produce the inedible animal tallow methyl ester. Biodiesel from waste cooking oil was produced from waste cooking oils and methyl alcohol via a transesterification reaction, and provided by a commercial biodiesel producer. In order to investigate the performance and exhaust emissions, the experiments were conducted at different engine speeds under the full load condition of the engine. The experimental results showed, compared with diesel fuel, that the biodiesel fuels resulted in a reduction in brake torque and in an increase in brake specific fuel consumption. Although both biodiesels caused reductions in carbon monoxide (CO), the NOx emissions were higher for waste cooking oil biodiesel and lower for inedible animal tallow biodiesel as compared to diesel fuel.Öğe Experimental investigation of solar stills integrated with solar water heating collectors(Türk Isı Bilimi ve Tekniği Derneği, 2017-10-31) Argunhan, Zeki; El, Emin; Yıldız, Cengiz; Çakmak, GülşahSolar still is a more practical way of obtaining clean water. In this study, we aimed to improve the efficiency of solar still systems and obtain distilled water at the same time. For this purpose, 5 different solar still systems were designed. Type 1; conventional solar still, Type 2; conventional solar still integrated with solar water heating collector and run via natural convection, Type 3; conventional solar still integrated with solar water heating collector and tubular heat exchanger and run via natural convection, Type 4; conventional solar still placed with plate heat exchanger and integrated with solar water heating collector and run via natural convection, Type 5; conventional solar still placed with plate heat exchanger and integrated with solar water heating collector and run via forced convection. In this study, the experiments were carried out on the parameters influencing the performance, the amount of distilled water obtained, and the efficiency of experiment settings designed in different types; and finally the results were presented. The amount of distilled water and efficiency of conventional solar still were 2389 ml and 51.47%, respectively. Maximum total amount of water and efficiency from natural convection systems were obtained from Type 4, and the values calculated were found as to be 5788 ml and 55.91%. Maximum amount of distilled water and the efficiency were obtained by utilizing forced convection system were found as to be 6068 ml and 58.99%, respectively.Öğe Modelling of effects of various chip breaker forms on surface roughness in turning operations by utilizing artificial neural networks(Gazi Üniversitesi, 2016-03-01) Gürbüz, Hüseyin; Baday, Şehmus; Sözen, AdnanIn this study, the effects of different chip breaker forms and cutting parameters on the surface roughness on machined surfaces were investigated experimentally in turning of AISI 1050 steel; and values of surface roughness obtained from experiments were determined with empirical equations using artificial neural networks. The utilizing of ANN was offered to determine the surface roughness depending on chip breaker forms and cutting parameters of AISI 1050 steel. The back propagation learning algorithm and fermi transfer function were used in artificial neural network. Experimental measurements data were employed as training and test data in order to train the neural network created. The best fitting training data set was attained with ten neurons in two hidden layers 6 of which were at first hidden layer and 4 of which were at second hidden layer, making it possible to predict surface roughness with precision at least as good as that of the experimental error over the entire experimental range. After network training, R2 value was found as 0.978, and average error as 0.018%. When the results of mathematical modelling are examined, the computed surface roughness is observed to be apparently within acceptable valuesÖğe The effects of apricots seed oil biodiesel with some additives on performance and emissions of a diesel engine(International Journal of Automotive Engineering and Technologies, 2016) Aydın, Hüseyin; Hanbey, Hazar; Uyar, Mahmut; Şap, EmineThe purpose of this experimental work is to investigate influences of using manganese (Mn) as a combustion catalysts on apricot seed oil based biodiesel production and its engine out parameters. The metal based additive (Mn) was added to biodiesel (B50) at different dosages of 20-40-60 μmol/L. Also, other additives the propylene glycol and dodecanol were added into apricot seed oil biodiesel (B50) at rates of 5% and 1%, respectively for preparing test fuels.This additives improved flash point, pour point and viscosity of the biodiesel (B50) fuel. Experiments were carried out to clarify the effects of all additives added to biodiesel on performance and emission characteristics of a three-cylinder DI diesel engine operated at a constant speed of 1500 rpm and different loads from 2,50 to 10 kW. The engine test results revealed that specific fuel consumption, NOx were not changed significantly with the adding additives to biodiesel (B50) fuel, while CO, HC and smoke emission profiles were improved.Öğe Characterization of medieval glass from Cizre Castle excavation by SEM-EDS and P-EDXRF analyses(Türkiye Bilimler Akademisi, 2020-06-15) Aydın, Mahmut; Güngör, Akarcan; http://dx.doi.org/10.22520/tubaar.2020.26.008Şırnak İli Cizre İlçesinde yer alan Cizre Kalesi Kazıları’nda 2013-2017 yılları arasında ele gecen cam örnekler arkeometrik yönden incelenmiştir. Cam örnekler öncelikle form özelliklerini yansıtacak şekilde görsel olarak tanımlanmış, fotoğraflanarak belgelenmiş ve kodlanmıştır. Cam örneklerinin yapım teknikleri hem görsel hem de taramalı mikroskop altında habbe şekillerine göre belirlenmeye çalışılmıştır. Örneklerin element ve mineralojik içerikleri taşınabilir Enerji dağılımlı X-ışınları floresans spektroskopi (P-EDXRF) ve Taramalı Elektron Mikroskobu-Enerji Dağılımlı Spektroskopi (SEM-EDS) yöntemleri ile analiz edilmiştir. Analiz sonuçları cam örneklerin 7 tanesi soda camı iken diğer 7 si potasyum kireç camı olduğu anlaşılmıştır. Örneklerin yüksek Si içerikleri, camların hem mekanik direnç ve dayanıklılığın, hem de ergime sıcaklığının yüksek oluşuna işaret etmektedir. Cam örneklerin üretiminde bir örnek hariç bitki külü (K ve/veya Mg) kullanılmamıştır. Cam örneklerin Al içeriklerindeki farklılık örneklerin hammadde adresini ayrı kaynaklara dayandırmaktadır. Sr ve Zr’nin tespit edilmemiş veya düşük oranlarda olması karasal hammadde kullanılmış olduğunu göstermektedir. Camlarda renk veren elementler; Fe, Co, Mn ve Cu’durÖğe Comparison of CLTD and TETD cooling load calculation methods for different building envelopes(Mugla Sitki Kocman University, 2020-06-30) Oktay, Hasan; Yumrutaş, Recep; Işık, Mehmet ZerrakkiThe estimation of the cooling load through the building envelope is an essential task in the selection of proper HVAC system components that influences the building’s performance. For this task, ASHRAE has presented several methods to calculate the building cooling load due to heat gain, such as the total equivalent temperature difference method (TETD), the cooling load temperature difference method (CLTD), and the radiant time series method (RTS). The present study aims to explore the accuracies of those calculation methods in terms of energy efficiency. In this regard, an analytical solution method utilizing Complex Finite Fourier Transform Technique (CFFT) was developed for the calculation of cooling load due to heat gain to compare the temperature differences obtained from the TETD and CLTD methods. Then, a computer program was prepared in MATLAB to perform the calculations based on an analytical methodology. Besides, the estimated CLTD and TETD values by the CFFT were compared with those values presented in the Handbook of the ASHRAE. The calculation results revealed there is a good agreement between the analytical and presented results in the ASHRAE Manual for the selected building envelopes. However, several differences were found between the estimated TETD and CLTD cooling load values and those presented in the Handbook of ASHRAEÖğe A novel approach for extracting ideal exemplars by clustering for massive time-ordered datasets(TÜBİTAK, 2017-07-30) Ertuğrul, Ömer FarukThe number and length of massive datasets have increased day by day and this yields more complex machine learning stages due to the high computational costs. To decrease the computational cost many methods were proposed in the literature such as data condensing, feature selection, and filtering. Although clustering methods are generally employed to divide samples into groups, another way of data condensing is by determining ideal exemplars (or prototypes), which can be used instead of the whole dataset. In this study, first the efficiency of traditional data condensing by clustering approach was confirmed according to obtained accuracies and condensing ratios in 9 different synthetic or real batch datasets. This approach was then improved to be employed in time-ordered datasets. In order to validate the proposed approach, 23 different real time-ordered datasets were used in experiments. Achieved mean RMSEs were 0.27 and 0.29 by employing the condensed (mean condensed ratio was 97.17%) and the whole datasets, respectively. Obtained results showed that higher accuracy rates and condensing ratios were achieved by the proposed approach.Öğe Comparison of heat gain values obtained for building structures with real and constant properties(Bitlis Eren Üniversitesi, 2019-12-24) Oktay, Hasan; Yumrutaş, Recep; Argunhan, ZekiThe magnitude of energy consumption due to the heating and cooling of buildings has led to the demand for increasing the thermal performance of building structures. Many investigations are presented in literature arguing to find the effect of each thermophysical property on the thermal characteristics of building components, while the properties have been assumed as independent of each other. In this context, this paper focuses on the effect of each property on heat gain value utilizing relationships between the measurement values of the thermophysical properties of building structures. In the previous study, 102 new wall samples were produced, their thermophysical properties were tested and expressions among these properties are obtained. In this study, the heat gain values through the structures are computed using the solution of the transient heat transfer problem by using both the obtained expressions between the thermophysical properties and assumptions proposed from the literature. Results obtained for varying and constant thermophysical properties have been compared with those values presented in the literature. The results show that the assumptions are not realistic in a significant number of cases. Moreover, if one of the thermophysical properties of a material is known, heat gain values can be calculated easily for the selected wall or roof types.
