2021 Cilt 26 Sayı 2

Permanent URI for this collectionhttps://hdl.handle.net/11452/27800

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Analysis and comparison of the fuel properties of bio-oils produced by catalytic fast pyrolysis of tectona grandis
(Bursa Uludağ Üniversitesi, 2021-08-13) Okekunle, Pious O.; Ogunsola, Akinola D.; Babayemi, Oluwapelumi A.; Abodunrin, Emmanuel D.; Daramola, Olanrewaju M.
This study analyzed the fuel properties of bio-oils produced by catalytic fast pyrolysis of Tectona grandis in a fixed bed reactor at different temperatures (400 – 600°C) and biomass to catalyst (b/c) weight ratios (90/10 – 60/40). Magnesium oxide (MgO) was used as catalyst. The product yields were determined. Bio-oils were characterized with their elemental composition and their Higher Heating Values (HHVs) as well as their basic fuel properties at maximum bio-oil yields conditions, including viscosity, flash point, moisture content, pH value and Conradson Carbon Residue (CCR), were determined and compared with those of non-catalytic pyrolysis bio-oils. The maximum yields of bio-oil at 400, 500 and 600°C were 31.53, 40.87 and 29.30 wt.%, respectively, obtained at b/c ratios of 70/30, 80/20 and 70/30. Catalytic pyrolysis bio-oils possessed higher carbon and hydrogen but lower oxygen and sulphur contents than non-catalytic pyrolysis bio-oils. The HHVs of catalytic pyrolysis bio-oils (40.31 – 42.08 MJ/kg) were higher than those of non-catalytic bio-oils (36.47 – 36.76 MJ/kg). Catalyst reduced the viscosity (at 400 and 500°C), moisture content and CCR (at 400 and 600°C), and increased the pH value of bio-oils (at 400 and 600°C). Catalytic pyrolysis deoxygenates and enhances the fuel properties of bio-oils.
Dynamic stability analysis of the laminated composite curved frame structures
(Bursa Uludağ Üniversitesi, 2021-07-08) Daş, Oğuzhan; Öztürk, Hasan; Gönenli, Can
In this study, the dynamic stability analysis of the laminated composite single-bay and two-bay curved frame structures has been investigated. For this purpose, a computer code is written in MATLAB to evaluate the natural frequency values, critical buckling load, and first unstable regions of the laminated composite curved frames. The effects of radii of curvature and stacking order on the static and dynamic stability of both single and two bay arch frame structures are investigated. Besides, the effects of the stacking order are investigated by considering five different stacking sequences. The results of the present study are compared with the results obtained numerically via ANSYS for validation. It is concluded that the radius of curvature has a small effect on the first five natural frequency values, buckling loads, first unstable regions of the structure, whereas the fiber orientation considerably has a considerable impact on such static and dynamic properties.
Estimation of pain threshold from EEG signals of subjects in physical therapy using long-short- term memory deep learning model
(Bursa Uludağ Üniversitesi, 2021-06-28) Güneç, Kutay; Kasım, Ömer; Tosun, Mustafa; Büyükköroğlu, Emine
Pain is a natural stimulation to protect the whole body. An overreaction to pain can damage the tissues. Therefore, it is important to know the angle at which pain is felt when routinely measuring joint range of motion during the first examination. Detection of pain with the change in characteristics of electroencephalogram signals at the moments when pain occurs is the novelty of this study. The characteristics of the signal with power band changes were obtained by frequency analysis of the electroencephalogram signals. Pain was detected by classifying these characteristics with the Long Short Term Memory deep learning model. Validation of the model was performed with records obtained from 43 volunteer subjects with a 14-channel wireless Emotive brand electroencephalogram device. 96.1% success in binary classification as with pain or without pain and 89.6% success in multi-class classification as with high pain, low pain and without pain was achieved. This success is a quality that can support specialists in diagnosis and treatment by determining the threshold where pain occurs during the first physical therapy examination from the electroencephalogram signals.
Influence of linear profile modifications on the dynamic loading of a spur gear
(Bursa Uludağ Üniversitesi, 2021-05-21) Doğan, Oğuz; Kalay, Onur Can; Karpat, Fatih; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.; 0000-0001-8643-6910; 0000-0001-8474-7328
Gear dynamics is one of the most critical subjects in gear design because of its remarkable effect on vibration levels, load-carrying capacity, and noise. The tip relief modification is known as a simple method to decrease dynamic loads in the industry. The primary goal of this study is to understand the influence of tip relief modification on the dynamic performance of the spurs gears. In this paper, the meshing process and gear mesh stiffness calculation method are defined. A dynamic model with two- degree-of-freedom is created to find the dynamic response of the spur gear pair. The simulations are carried out with standard and different tip modified spur gear pairs. It is observed that the tip relief modification has an excellent effect on the gear dynamic response. However, this effect is restricted until a certain amount of tip relief modification. After the optimum amount of tip relief modification, the dynamic loads are increased considerably. Thus, a computer program is developed to find the optimum amount of tip relief modification in MATLAB® for the gear designers. The program outputs are given for two different case studies. As a result of the study, the dynamic factor behaves like a “V form” according to the tip relief modification, and the dynamic force decreased approximately 25% for optimum profile modification.
Statistical analysis and evaluation of PM concentrations during the dust storms at may 2020 for Selçuklu district of Konya city, Turkey
(Bursa Uludağ Üniversitesi, 2021-05-08) Kunt, Fatma; Ayturan, Zeynep Cansu; Dursun, Şükrü
Dust storms are widespread events that occur several times a year and spread over many countries of the world relating the wind direction and speed. Especially particulate matter (PM) is the main pollutant spread over by these storms. Because of the dust storms, PM concentrations increase rapidly in the areas found on the way of dust storm passes In this study, statistical evaluation was made accordingly the PM data measured with personal measurement device in Selçuklu District of Konya and the meteorological and the air pollution data provided from air quality monitoring station, which is affiliated by the Ministry of Environment and Urbanization, located nearby. Pearson correlation test has been applied to both data sets and a significant relationship has been detected between the measured and provided data. Moreover, multiple linear regression was applied to the data for PM2.5 and PM10 separately. Adjusted R2 of the analysis has been found as 0.573 and 0.559 respectively for PM2.5 and PM10 which explains almost half of the relationship between PM and meteorological variables. The highest positive effect on PM pollution was determined as air temperature. Finally, principal component analysis (PCA) was applied to both data and 4 different principal components were detected. Measured PM2.5 and PM10, air temperature, and relative humidity were clustered at the same component group.

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