2023 Cilt 28 Sayı 2

Permanent URI for this collectionhttps://hdl.handle.net/11452/41018

Browse

Now showing 1 - 9 of 9

The effect of phase change materials on room temperature for winter and summer
(Bursa Uludağ Üniversitesi, 2023-07-17) Soğukpınar, Hacı; Bozkurt, İsmail
The efficient use of our existing energy resources is as important as finding new energy sources, since the demand for energy is increasing day by day. Heating and cooling loads in buildings constitute a large part of energy consumption. Therefore, it is very important to improve the energy performance of buildings. The utilization of phase change materials to increase the energy efficiency of buildings is one of the recent research topics. In this study, the effect of phase change materials on room temperature for winter and summer months was investigated numerically by defining real environmental conditions in the virtual environment. Phase change material with thermophysical properties suitable for Mediterranean climate conditions was selected for summer and winter. It can keep the room temperature at a slightly lower level during the daytime in summer and the room temperature higher in winter than in the insulated state case. As a result, phase change materials can be used as a natural air conditioner in the summer, as well as a natural heater at night in the winter. On the other hand, smart bricks can be produced that can absorb the heat transmitted from the inside to the outside by using different phase-change materials.
The experimental and numerical investigation of the thermal behaviors of a jacketed heat exchanger with a stirrer
(Bursa Uludağ Üniversitesi, 2023) Bayram, Halil; Cesur, Mert; Sevilgen, Gökhan; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Otomotiv Mühendisliği Bölümü; 0000-0002-7746-2014
In this study, the thermal performance of a jacketed heat exchanger with a stirrer was experimentally and numerically investigated under different jacket side water inlet temperature and flow rate conditions. In the numerical study, a three-dimensional computational fluid dynamics (CFD)model of the heat exchanger was generated and the analyzes were performed with the ANSYS-Fluent software package. In addition, a stirrer was added to both the experimental and the numerical study to obtain the effects of the stirrer on the temperature and velocity values of the water in the tank. It was seen that the results of the analyzes performed under similar conditions to the experimental study were in good agreement with the experimental study. It was concluded that the effect of the flow rate decreases with increasing inlet temperature. When the stirrer was activated and the flow rate was increased from 0.5 to 2.5 l/min in 30, 40, and 50°C inlet temperature conditions, the time to reach the target temperature inside the tank decreased from approximately 1600 to 900, from 2500 to 1350, and from 4900 to 1400, respectively. In general, it was observed that the effect of the stirrer increased with increasing inlet temperature in all flow rate conditions.
Green photocurable phosphorus containing coatings on cotton fabrics
(Bursa Uludağ Üniversitesi, 2023-07-03) Yıldız, Zehra
In this work, a bio-based, lightweight, coated cotton fabric by using a cleaner manufacturing method, “photocuring” was proposed in order to be used as an alternative to the conventional heat-, solvent-, and waterbased outdoor textile (tarpaulin, tent, etc.) manufacturing. For this purpose, photocurable bio-based phosphorylated oligomer was synthesized with the reaction between a monomethacrylate functional phosphorus containing monomer and epoxidized soybean oil (ESBO). The synthesized phosphorylated ESBO (P-ESBO) oligomer was used in cotton fabric coatings in different proportions and photocured with UV light exposure. The effects of the amount of P-ESBO oligomer in the formulation on the crystalline morphology, mechanical, thermal, surface wettability, flammability, and abrasion resistance properties of the cotton fabrics were all searched. It was revealed that the increasing amount of P-ESBO oligomer in the formulation increases the drapeability and tensile strength of the fabrics with enhanced flame resist property by giving higher char yields. Besides, phosphorylated oligomer also acted as an adhesion promoter between the fabric surface and coating layer resulting a better abrasion resistance property.
Hybrid approximation method for time response improvement of cfe based approximate fractional order derivative models by using gradient descent algorithm
(Bursa Uludağ Üniversitesi, 2023-04-17) Köseoğlu, Murat; Deniz, Furkan Nur; Alagöz, Barış Baykant
Due to its high computational complexity, fractional order (FO) derivative operators have been widely implemented by using rational transfer function approximation methods. Since these methods commonly utilize frequency domain approximation techniques, their time responses may not be prominent for time-domain solutions. Therefore, time response improvements for the approximate FO derivative models can contribute to real-world performance of FO applications. Recent works address the hybrid use of popular frequency-domain approximation methods and time-domain approximation methods to deal with time response performance problems. In this context, this study presents a hybrid approach that implements Continued Fraction Expansion (CFE) method as frequency domain approximation and applies the gradient descent optimization (GDO) for step response improvement of the CFE-based approximate model of FO derivative operators. It was observed that GDO can fine-tune coefficients of CFE-based rational transfer function models, and this hybrid use can significantly improve step and impulse responses of CFE-based approximate models of derivative operators. Besides, we demonstrate analog circuit realization of this optimized transfer function model of the FO derivative element according to the sum of low pass active filters in Multisim and Matlab simulation environments. Performance improvements of hybrid CFE-GDO approximation method were demonstrated in comparison with the stand-alone CFE method.
Investigating the effect of feature selection methods on the success of overall equipment effectiveness prediction
(Bursa Uludağ Üniversitesi, 2023-07-13) Yılmaz, Ümit; Kuvat, Özlem
Overall equipment effectiveness (OEE) describes production efficiency by combining availability, performance, and quality and is used to evaluate production equipment’s performance. This research’s aim is to investigate the potential of the feature selection techniques and the multiple linear regression method, which is one of the machine learning techniques, in successfully predicting the OEE of the corrugated department of a box factory. In the study, six different planned downtimes and information on seventeen different previously known concepts related to activities to be performed are used as input features. Moreover, backward elimination, forward selection, stepwise selection, correlation-based feature selection (CFS), genetic algorithm, random forest, extra trees, ridge regression, lasso regression, and elastic net feature selection methods are proposed to find the most distinctive feature subset in the dataset. As a result of the analyses performed on the data set consisting of 23 features, 1 output and 1204 working days of information, the elastic net - multiple linear regression model, which selects 19 attributes, gave the best average R2 value compared to other models developed. Occam's razor principle is taken into account since there is not a great difference between the average R2 values obtained. Among the models developed according to the principle, the stepwise selection - multiple linear regression model yielded the best R2 value among those that selected the fewest features.
Investigation of the effect of process parameters in CO2 laser cutting of PMMA material by response surface method
(Bursa Uludağ Üniversitesi, 2023-07-14) Kurt, Emre; Karaçay, Umut Efe; Tutar, Mümin
Recently, the studies on lightweighting have gained significant importance due to requirements such as energy efficiency and sustainability. Polymer materials are a group of materials that are frequently used for this purpose. This study investigated the effects of laser power, cutting speed and focal point on the kerf width, which are the most effective process parameters in laser cutting of Polymethylmethacrylate, a low-cost polymer material, using Response Surface Methodology and ANOVA. The results obtained from the data analysis show that the kerf width is seriously affected by the focal point depth as well as the speed and power.
A laboratory scale investigation of manning roughness coefficient in open channel bed with different grain size and slopes
(Bursa Uludağ Üniversitesi, 2023-07-11) Yılmaz, Damla; Aras, Egemen; Vaheddoost, Babak
Efforts for getting the maximum efficiency from the existing water resources and to implement new projects are getting more attention these days. Determining the flow resistance for the project design and control process in open channels requires sophisticated applications. It is usually essential to be aware of the characteristics of the channel and flow to determine the hydraulic roughness, which represents the resistance of the flow. Hence, empirical calculation and evaluation of the hydraulic roughness will support future design and planning processes. In this study, four different particle sizes (d50= 28mm, 17.5mm, 4mm, and 1.75mm) that were fixed on blocks were used. These particle sizes were then used as the bed covering together with, three different horizontal bed slopes, and flow rates in the experiments to determine the associated Manning roughness, n. During the experiment, Froude number values were examined and it was determined that, in 32 experiments the flow regime can be considered as subcritical. Alternatively, the Lotter method was used to confirm the roughness values obtained by the Manning equation. It was concluded that the roughness values obtained by the selected methods have good concordance with each other.
An lot based application on the detection of car parking area by an artificial intelligence approach
(Bursa Uludağ Üniversitesi, 2023-07-14) Karakaya, Oğuzhan; Gültekin, Fikret Mert; Başkaya, Mert; Doğan, Yunus
Nowadays, smart cities solutions have been becoming popular day by day. The problem of finding a parking place is one of these implementations. Our study appeals to users who want to park their vehicle quickly and who want to find out whether the parking place is available to park before searching for a parking place. This application aims to find a solution to the problem of searching for a place to park. We have found a novel solution to this problem by using image processing methods and utilizing photographs of streetside parking places in the most effective way. In addition, an Android software has been developed through which we can deliver the results obtained with the image processing module to users via a mobile application. As a result, a parking IoT determination system has been implemented in this study with 92% accuracy value. Thanks to this system, vehicle owners who want to park their vehicles on the side of the street will be able to learn whether the parking places in a street are available in advance and they will be able to save their time by preferring more available streets.
Plastic joining methods: Ultrasonic and vibration welding
(Bursa Uludağ Üniversitesi, 2023-07-25) Kıyılı, Onur
Plastic welding is a common method for manufacturing parts that can’t be molded and has a complex geometry such as the part that has undercuts. The process is suitable for mass production, cheap and meets automotive requirements. The process helps the zero-emission target of the automotive industry, due to the biggest obstacle of the plastic use in this sector was the moldability of the complex geometries. Most of the engine parts such as thermostat, water pump etc. can’t be molded as one piece. These engine components are manufactured by helping the plastic welding and decrease the weight of the automobile, therefore, improving fuel efficiency. Plastic welding technology has become more important especially in electrical vehicles, because metal to plastic replacement has a significant role in decreasing the weight of the vehicle. Selecting the welding method according to the polymer properties and the geometry of parts are the most important factors for the application area. All of the welding methods are basically based on the remelting of the welding surfaces of the parts and the consolidation of them under the pressure. In this paper, the vibration welding and the ultrasonic welding methods have been inspected. The most effective parameters of both processes have been discussed and shown.

Browse

Browsing by Language "en"