Uludağ Üniversitesi Mühendislik Dergisi / Uludağ University Journal of The Faculty of Engineering

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A DC~1.6 GHz distributed amplifier with GaAs MESFETs
(Uludağ Üniversitesi, 2016-08-31) Hiçdurmaz, Bahadır; Özzaim, Cengiz
In this study, a DC ~ 1.6 GHz bandwidth distributed amplifier (DA) is fabricated in printed circuit board (PCB). The scattering (S-) parameters of the distributed amplifier are measured and compared with simulated results. In characterization of the amplifier, small-signal microwave Sparameters given at some discrete frequencies of transistors are utilized. According to obtained results, it is observed that measured and simulated results are in relatively good agreement.
A refrigerated road transport application
(Uludağ Üniversitesi, 1999) Horuz, İlhamı; Mühendislik Mimarlık Fakültesi; Makine Mühendisliği Bölümü
The study included an investigation into the use of Vapour Absorption Refrigeration (VAR) systems in road transport vehicles using the waste heat in the exhaust gases of the main propulsion unit as the energy source. This would provide an alternative to the conventional Vapour Compressian Refrigeration (VCR) system and its associated Internal Combustion (IC) Engine. The proposed system is almost maintenance free, having only one component, the solution pump, with moving parts. Additionally, the VAR system runs quietly and primary fuel energy used to drive the independent engine of the VCR system will be saved. There should also be savings in capital costs with the exclusion of the IC engine and the compressor of the conventional system. The effect on the main propulsion unit of inserting the VAR system into the exhaust system and how cooling can be provided during off-road/slow running conditions are also included in the studies.
Aerodynamic mechanisms on a ground-mounted solar panel at different wind directions
(Bursa Uludağ Üniversitesi, 2020-03-05) Yemenici, Onur; Mühendislik Fakültesi; Makine Mühendisliği Bölümü; 0000-0003-0011-8343
Aerodynamics mechanisms on a solar panel were studied using Computational Fluid Dynamics methodology at different wind directions. The wind velocity was chosen as 10 m/s that corresponding turbulent flow. The inclination angle of the panel was fixed as 25°, while the wind directions were varied as 180°, 135°, 45°, and 0°. Governing equations were solved by utilizing a finite volume method with a realizable k-ε turbulence model and standard wall functions. The results showed that the recirculation area occurred for the straight wind directions, but it was not observed for the oblique wind directions. The highest pressure coefficients occurred at the leading edges of the solar panel and they reduced to the trailing edge for all wind directions. The maximum drag and uplift coefficient was obtained at the wind direction of 00 and 180 0 , respectively.
Alternative lightweight composite facing members for reinforced soils
(Bursa Uludağ Üniversitesi, 2023-11-13) Evirgen, Burak; Tunaboyu, Onur; Büyük, Barış; Çil, Gizem Tuğçe
Steel reinforced concrete facing members, which are used to fix geosynthetic reinforcements working against tensile forces inside soils and to resist active lateral earth pressures, have certain disadvantages, such as massiveness and corrosion. In addition, the aforementioned conventional panels arenot economical since they frequently require maintenance and repair in terms of long-term stability. In thisstudy, the utility of alternative composite panels is evaluated with the various arrangement and type of fiberreinforcements and a typical foam concrete. Panel tests and three-point bending tests are realized to determine the experimental behavior of steel, carbon fiber (CFRP) and glass fiber reinforced (GFRP) specimens, as well as unreinforced examples. Although CFRP wrapped specimens cannot reach expectedlevels, samples with GFRP present favorable performance as well as being cheaper. Specimens with matGFRP enhance both strength and deformation capacities according to the results of axial and lateraldeformations under diagonal loading condition. In addition, chopped GFRP applied foam concret especimens have more strength in terms of bending test results, but CFRP reinforcements increase the irdisplacement capacity.
Ambient vibration analysis of an industrial building
(Bursa Uludağ Üniversitesi, 2021-01-03) Kartal, Hüseyin; Dere, Yunus; Arslan, Musa Hakan
Due to the heavy and dynamic equipment, the vibration and resonance effects that are not encountered under static dead loading may amplify over time in industrial buildings. This might cause damage to the structural system and create human comfort problems while the structure is in service. In this study, ambient vibration testing of a building composed of reinforced concrete and steel structural systems and located at a boron processing plant in Turkey was performed. The velocities and accelerations caused by the sieve shaker system attached to the structure with springs, are evaluated under the effect of sample loading.
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.
Analysis of material position and size in a waveguide fed resonator
(Uludağ Üniversitesi, 2016-02-09) Kent, Sedef; Süle, Okan; Mühendislik Fakültesi; Elektrik Elektronik Mühendisliği Bölümü
The main factors that affect electric field distribution, and therefore heat distribution, are the dimensions of the resonator, heating frequency, shape and dielectric properties of the material to be heated, position of the material to be heated within the resonator and the position of the feed guide on the resonator. From among these factors that directly affect heating, this work examined the material thickness. The purpose of this study was to determine the material thickness that will minimise the reflection coefficient. The accuracy of the results obtained by means of the mode matching method was demonstrated by comparing those results with the results obtained through Ansoft’s High Frequency Structure Simulator.
Analysis of selection diversity on the matched filter bound of bpsk on multipath rayleigh fading channels
(Uludağ Üniversitesi, 2004) Ertaş, Tuncay; Mühendislik Mimarlık Fakültesi; Elektronik Mühendisliği Bölümü
The impact of diversity combining on the matched filter bound of BPSK on time-discrete multipath slowly Rayleigh fading intersymbol interference channels is analysed. Expressions for the bound are derived for SNR selection, S+N selection, and also equal gain diversity combining. Numerical results for the derived bounds are presented on a GSM typical urban channel model.
Analysis of signal-to-crosstalk ratio variations due to four-wave mixing in dense wavelength division multiplexing systems implemented with standard single-mode fibers
(Uludağ Üniversitesi, 2016-09-23) Karlık, Sait Eser; Mühendislik Fakültesi; Elektrik Elektronik Mühendisliği Bölümü
In this paper, variation of the signal-to-crosstalk ratio (SXR) due to effects of four-wave mixing (FWM) has been analyzed on center channels of 5-, 7-, 9-channel dense wavelength division multiplexing (DWDM) systems implemented with G.652 standard single-mode fibers (SSMFs) for 12.5 GHz, 25 GHz, 50 GHz and 100 GHz equal channel spacing values. Center channels on such systems are the most severely impacted channels by FWM. Therefore, results obtained are the worst-case values for the DWDM system performance and important for system design. Simulations have been performed for systems using three different commercially available SMFs having different design parameter values for chromatic dispersion, dispersion slope, nonlinearity coefficient and attenuation coefficient which are all in the scope of the G.652 Recommendation of Telecommunication Standardization Sector of International Telecommunication Union (ITU-T) for SSMFs. In those simulations, under the impact of FWM, variation of SXR with variations in input powers, channel spacings and link lengths have been observed. Simulation results display the combined effect of the optical fiber and system design parameters on FWM performance of DWDM systems and give important clues for not only long-haul but also access network implementations of DWDM systems.
Analysis of surface plasmon resonance sensing based on phase-detection in the infrared range
(Bursa Uludağ Üniversitesi, 2018-10-17) Koç, Aykut
Using phase detection in Surface Plasmon Resonance (SPR) sensing has potential improvements to the conventional intensity detection based SPR. Other than the phase detection and intensity detection based SPR in the visible range of the spectrum, employing SPR sensing principles in the infrared range by the use of silicon has also some promising advantages. Combining these two, in this paper, phase detection-based SPR sensing in the infrared range is studied using a mathematical model and numerical simulations. The results are compared with the results obtained by the simulations in the visible range. Performance improvements are noted by the use phase detection in the infrared range.
An analytical approach for material synthesis based on shielding effectiveness characteristics
(Uludağ Üniversitesi, 2017-02-27) Erbaş, Cihan Döğüşgen; Kent, Sedef
We describe an analytical method to synthesize a Debye-like equivalent homogeneous material by computing the associated parameters such as static relative permittivity, relative high-frequency limit permittivity, relaxation time, and the width of the material for a given shielding effectiveness specification and a given range of frequency as well as material width. We illustrate the parameter extraction procedure with a numerical example, in which we validate that the applied method is able to produce the desired SE profile within the specified frequency range.
Analytical investigation of curvature ductility of reinforced concrete columns
(Bursa Uludağ Üniversitesi, 2020-01-12) Foroughi, Saeid; Yüksel, S. Bahadır
In this study; the effect of axial load, longitudinal reinforcement diameter, transverse reinforcement diameter and transverse reinforcement spacing were investigated on the moment curvature relationships of reinforced concrete columns. Reinforced concrete columns having different geometries were designed considering the regulations of Turkish Building Earthquake Codes (2018). Investigations of the effect of axial load, longitudinal reinforcement diameter, transverse reinforcement diameter and transverse reinforcement spacing on the behavior of the concrete columns are the main purpose of this study. The behavior of the columns was investigated from the moment-curvature relation, by considering the nonlinear behavior of the materials taken into account. The moment-curvature relationships of the reinforced concrete column cross-sections having different axial load levels have been obtained by considering Mander model which considers the lateral confined concrete strength. The examined effects of the parameters on the column behavior were evaluated in terms of curvature ductility and the moment capacity of the cross-section. In the designed column cross-sections, different parameters effecting the moment-curvature relationships were calculated and compared. It is observed that the variation of the axial load, longitudinal reinforcement diameter, transverse reinforcement diameter and transverse reinforcement spacing have an important effect on the moment-curvature behavior of the reinforced concrete columns.
Antimicrobial and water repellency performance of polypropylene outdoor fabrics subjected to sequential finishing processes
(Bursa Uludağ Üniversitesi, 2021-10-19) Günaydın, Gizem Karakan; Çeven, Erhan Kenan; Kut, Dilek Toprakkaya; Mühendislik Fakültesi; Tekstil Mühendisliği Bölümü; 0000-0003-3283-4117; 0000-0002-9059-0838
Polypropylene fabrics are one of the most preferred products for outdoor textiles. With the risks posed by the pandemic in the last year, outdoor textiles are expected to have some additional features such as antibacterial, antivirus, antimildew properties. Antimicrobial finishing and water repellency treatment may be applied consecutively on polypropylene fabrics. This research aims to investigate the effect of sequential finishing process by applying of different antimicrobial chemical ratio (0, 5 and 10 g/l) and fluorocarbon-based water repelling substance (0, 30 and 50 g/l) on antimicrobial efficiency and water repellency grades of outdoor fabrics. According to the results of statistical analyses, it was determined that antimicrobial efficiency against S. aureus and C. albicans was statistically influenced from process type at significance level of 0.05, while antimicrobial efficiency against E.coli microorganism was not statistically influenced from process type. Antimicrobial activity of outdoor samples was more satisfying against S. aureus microorganism. Water repellency results generally improved as the applied amount of water repellent substance increased for the fabrics treated with the same amount of antimicrobial substance.
An application of the aircraft identification
(Uludag Universitesi, 1993) Ture, Murat; Uludag Universitesi; Muhendislik Mimarlık Fakultesi; Elektronik Mühendisligi Bolumu
In this study, a solution of an aircraft identification problem is presented. Firstly, the essential equations of longitudinal motion are introduced and simplified. Subsequently, this motion is simulated with a suitable model as a real aircraft. Finally, the model system has been identified in real time for different environmental condition.
Approximate expressions for worst and best case Cramér-Rao bounds for estimating the parameters of close cisoids
(Uludağ Üniversitesi, 2003) Dilaveroğlu, Erdoğan; Mühendislik Mimarlık Fakültesi; Elektronik Mühendisliği Bölümü
We present accurate approximations to the worst and the best case Cramér-Rao bounds for estimating the parameters of two closely spaced cisoids observed in additive complex white Gaussian noise. The approximations are valid in the sub-Rayleigh region where the difference between the critical values of the bounds becomes important.
An architectural desing studio in approach: “Galata experience”
(Uludağ Üniversitesi, 2010-12-22) Çetinkaya, Haluk; Deniz, Özgür; Akıncıtürk, Nilüfer; Çağlı, Yıldız; Erbil, Yasemin; Gür, Miray; Mühendislik Mimarlık Fakültesi; Mimarlık Bölümü
This study has been brought about due to the projects carried out in our country in recent years under the name of “transformation”. We believe it is both valuable and necessary that these transformation projects, which involve individuals who take part in the academic process and who are concerned with studio education, should also be dealt with in the architectural education process. Formed out of this idea, the “architectural design studio” was conceived with the aim of enabling students to “re-think” the above concepts and, by creating various projects in this context, of increasing their “internalisation” and “awareness” of the subject. In this case study, concepts such as urban transformation, urban change and urban environment, which are the “artificial” and, unfortunately, “sterile” concepts mentioned above, are discussed with the “Galata experience” on the basis of the students’ designs.
An artificial neural network (ANN) approach for solution of the transcendental equation of longitudinal vibration
(Bursa Uludağ Üniversitesi, 2019-02-20) Emül, Abdullah; Orhan, Sadettin; Aktaş, Gözde Rabia; Mühendislik Fakültesi; Makine Mühendisliği Bölümü
Study of mechanical vibration is one of the major issues in engineering applications. Especially, during the design and test stages of a mechanical component or system, vibration must be considered. When a vibration issue is studied theoretically, a differential equation called characteristics equation or equation of motion (EOM) is obtained. A solution of EOM gives vibrational behavior of an object considered. When vibration of a continuous system is studied, a transcendental equation is finally obtained, whose solution by classical methods is not possible. In this study, the solution of the transcendental equation which is derived from the longitudinal vibration of a bar with one end fixed and a mass at the other end was presented. For this purpose, an ANN model was constructed and the datasets were created for the ANN model. The effects of the number of neurons, input data, and training function on the model were examined. In addition, multiple regression models were developed using the ANN data also natural frequency formulation was obtained by ANN analysis for each mode. A finite element modal analysis was performed by ANSYS software. The results obtained by ANN and ANSYS were compared with analytic calculation and it was shown that they were in enough agreement.
Assessment of water and wastewater potential of Bursa city
(Uludağ Üniversitesi, 2017-03-02) Teksoy, Arzu; Nalbur, Berrak Erol; Solmaz, Seval Kutlu Akal; Mühendislik Fakültesi; Çevre Mühendisliği Bölümü
Urban growth is increasing the demand for freshwater resources and water is of significant importance for cities. Many fast growing megacities are facing serious water-related problems including pollution, eutrophication, missing wastewater treatment and perhaps most importantly, a severe scarcity of clean water. In the entire urban world, water resources are used in an inefficient way. Bursa is one of the wealthiest cities in terms of its supply of drinking and general purpose water in Turkey. Apart from rich freshwater resources Bursa has also thermal water springs. Bursa can be a sample city with its environmentally respectful water management system and foresighting in terms of water resources and wastewater treatment facilities.In this paper, Bursa a metropolitan city located in South Marmara Region of Turkey and which has come into prominence with wealthy water resources was evaluated in terms of water consumption and water resources. Several recommendations were scrutinised in order to protect current water capacity and proper usage of water for a planned and well-designed water management of the city. Wastewater treatment facilities were also stated within the frame of the paper. This paper concludes by suggesting ways of enhancing the resources of water and wastewater services in Bursa.
Asymptotic evaluation of scattering of inhomogeneous plane waves by a perfectly electric conducting half plane
(Bursa Uludağ Üniversitesi, 2019-04-26) Kara, Mustafa
In the present study, reflected and diffracted fields of an inhomogeneous plane wave obliquely incident on the surface of a perfectly electric conducting (PEC) half plane are evaluated for a two-dimensional case asymptotically and reexamined by considering the different aspects. Obtained results are plotted by Matlab numerically. Relationships between the complex angle of incidence and field intensities, and phase shifts in the fields are noted. Matlab plots are interpreted and compared to the theory for consistence.
Atmospheric organochlorinated pesticide levels and gas/particle partitioning in Istanbul during winter weather conditions
(Uludağ Üniversitesi, 2018-05-28) Kuzu, S. Levent
In this study, gas and particle phase ambient organochlorine pesticide (OCP) levels were investigated atan urban site in Istanbul. Samples were collected by a high-volume sampler for fourteen days in winter. Individual OCP concentrations were between13 and 593 pg.m-3 for particle phase and 14 and 1,748 pg.m-3 for gaseous phase. The sums of the average concentration of each OCP in gaseous and particle phases were 3,219 and 2,746 pg.m-3 , respectively. δ-HCH had the highest individual concentration. The abundance of DDTs followed the order 4.4'-DDT > 4.4'-DDD > 4.4'-DDE.The Σ(gas+particle)OCP concentrations ranged between 1,845 and 10,196 pg.m-3 . On the days when high concentrations were observed, the trajectories of air masses were investigated by the HYSPLIT model. logKp versus logPL 0 model was applied in order to determine the fate of gas/particle partitioning. The average slope of the regression line was -0.35, whereas the intercept was -2.89.

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