WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/8653
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Article Citation - WoS: 2Citation - Scopus: 2Ber Anaylsis for Super Lorentz-Gaussian Laser Beams Propagating in Turbulent Media(Gazi Univ, Fac Engineering Architecture, 2013) Gokce, Muhsin C.; Gökçe, Muhsin Caner; Sari, Filiz; Ozek, Faruk; Elektronik ve Haberleşme MühendisliğiIn this work, BER-SNR variation of super Lorentz-Gaussian laser beam that propagating horizontally path in turbulent media is analyzed. Using scintillation index which is obtained by extented Huygens-Fresnel principle, BER - SNR value is calculated. Matlab program is used to show BER - SNR variation depending on link distance and beamwidth. To conclude, in short link range, super Lorentz-Gaussian beam is proven to be better link performance superior to commercially available Gaussian beam.Article Citation - WoS: 9Citation - Scopus: 10Effect of Use of Cu-Cr P/M Electrodes on Machining Performance of Electric Discharge Machining(Gazi Univ, Fac Engineering Architecture, 2015) Gulcan, Orhan; Çoğun, Can; Uslan, Ibrahim; Usta, Yusuf; Cogun, Can; Çoʇun, Can; Mekatronik MühendisliğiIn this study, the effect of use of Cu-Cr powder metal (P/M) electrodes on EDM performance outputs, namely material removal rate (MRR), electrode wear rate (EWR), mean and maximum roughness of machined surface (R-a and R-z) and workpiece surface recast layer thickness, was investigated experimentally. The Cu-Cr P/M electrodes produced at different mixing ratios, compacting pressures and sintering temperatures were used to machine SAE 1040 steel. The analyses performed have shown that the electrode material is deposited on to the work surface as a layer and the powder mixing ratio, the compaction pressure and sintering temperature affect the EDM performance outputs.Article Citation - WoS: 3Citation - Scopus: 4An Analytical Investigation of Rigid Plastic Beams Under Impact Loading(Gazi Univ, Fac Engineering Architecture, 2015) Gultop, Tekin; Gültop, Tekin; Yilmaz, Mahmut Cem; Alyavuz, Bahadir; İnşaat MühendisliğiBeams might be subjected to impact loading which is a particular type of dynamic loading during their service lives. In this study the behaviour of beams under low speed impact loading has been investigated analytically. Simply supported and fixed ended beams have been analyzed with the assumption of rigid plastic behaviour. The collapse mechanism has been assumed to emerge by the instant formation of plastic hinges, hence, a limit analysis has been performed under dynamic loading considering the conservation principles of energy and momentum. The behaviour of rigid plastic beams under impact loading has been compared to the behaviour of elastic beams under similar loading conditions.Article Citation - WoS: 7Citation - Scopus: 7Development and Experimental Investigation of Electrochemical Drilling Method Using Rotary Tube Tool(Gazi Univ, Fac Engineering Architecture, 2013) Ozerkan, H. Bekir; Çoğun, Can; Cogun, Can; Mekatronik MühendisliğiIn this study, a new hybrid electrochemical drilling (ECD) method, based on electrochemical machining in nonconventional machining processes, was developed. In the developed method, tube tool makes rotary motion together with inner through hole flushing. A small scale prototype ECD machine has been designed and manufactured to test the developed method. One of the important features of the new system is the regulation of tool feed rate using current feedback control. The Hadfield (manganese) steel, whose strain hardening behavior makes it very difficult to machine with conventional methods, and AISI 1040 steel, whose machinability is fairly good, were drilled using the prototype machine and results were compared. Workpiece material removal rate increased with the increasing machining voltage, tool rotational speed, electrolyte concentration and flushing pressure in both types of steels. Average radial overcut values increased with the rotational speed of the tool. The AISI 1040 steel hole geometries were regular than that of Hadfield steel. Experimental results showed that deep holes can be drilled successfully with the proposed hybrid ECD method.Article Citation - WoS: 4Citation - Scopus: 4Influence of the Material Properties on the Elastic-Plastic Deformation in a Heat Generating Composite Solid Cylinder(Gazi Univ, Fac Engineering Architecture, 2013) Ozturk, Ali; Gülgeç, Müfit; Gulgec, Mufit; Mekatronik MühendisliğiBased on Tresca's yield criterion and its associated flow rule, the elastic-plastic deformation of a centrally heated composite cylinder with fixed ends is investigated by considering the influence of geometric parameters as well as material properties such as yield strength, modulus of elasticity, Poisson's ratio, coefficient of thermal conduction and thermal expansion. In the study, stress, strain and displacement distributions in the composite cylinder made of elastic-perfectly plastic material are derived. Stress distribution and evolution of plastic regions in the composite are presented for different levels of heat generation in the core.Article Citation - WoS: 3Citation - Scopus: 3Empirical and Statistical Modeling of Heat Loss From Surface of a Cement Rotary Kiln System(Gazi Univ, Fac Engineering Architecture, 2013) Simsek, Baris; Altunok, Taner; Simsek, Emir H.; Altunok, Taner; Makine MühendisliğiIn branches of industry too much energy consuming such as cement sector, controlled use of energy, only it is possible to know how energy is distributed in the system. In cement production process, a large portion of the heat losses which is due to energy consumption consist of convection and radiation heat losses from the surface of rotary kiln. In this study, empirical equation was derived for heat loss from surface of rotary kiln in a cement factory using empirical equations and statistical modeling techniques by the help of temperatures measured surface of rotary kiln. Measured with thermal cameras and the data necessary for experimental modeling was obtained the factory central control room. Total heat loss of system was calculated using Matlab. Statistical analysis related to results was carried out by Minitab 15.1.1 program. It was concluded that heat losses throughout rotary kiln increased toward the center of the kiln.Article Citation - WoS: 3Citation - Scopus: 4Numerical Analysis of a Commercial Display Cabinet With Air Curtain(Gazi Univ, Fac Engineering Architecture, 2011) Caliskan, Sinan; Altunok, Taner; Altunok, Taner; Baskaya, Senol; Gungunes, H. Murat; Makine MühendisliğiMaintaining food temperatures below critical values is the important maximising the high quality display life of chilled foods. Air curtains are especially used in stores and retailer supermarkets as barrier systems to seperate inner and outer spaces from each other. For both air quality and energy saving, it is crucial that the air transfer between these two spaces are at minimum. Minimization of air transfer between inner and outer spaces, not only decreases heat transfer but also stabilizes the humidity balance. In this study, numerical analysis of a commercial display cabinet has been carried out. For this purpose PHOENICS, a computational fluid dynamics code, is utilized. Optimum jet system conditions for each of the one jet, two jet and there jet systems has been modified according to temperature change of the air, and comparisons among them have been made. The results indicate that, the results the both CFD analysis and experimental results are almost equal and refrigeration systems with three jets is required to obtain the necessary temperature values to keep products fresh in display cabinets, especially because they can distribute temperature in a homogeneous way, meaning that the temperature value is the best ideal system at every point in the cabinet with three jets.Article Investigation of Factors Affecting Noise Robustness in Voice Activity Detectors(Gazi Univ, Fac Engineering Architecture, 2023) Ozaydin, SelmaIn this manuscript, some voice activity detectors (VADs) in the literature were examined in terms of factors affecting their robustness under different acoustic noise conditions and in this context, the changes in detection accuracy rates according to changing noise conditions were tested. In this scope, the effect of situations such as whether the threshold value used in the decision phase in VAD methods is fixed or adaptive, the analysis window is short or long, the use of more than one feature vector together has been evaluated and analyzed comparatively. While three of the four different VAD detectors examined in this manuscript use feature vectors within the short-term analysis window while generating the decision result, one decides according to the measurement result of long-term spectral vectors. The VAD detectors in the article have been tested using the NOIZEUS noisy speech database. Thus, the performance of the analyzed VADs has been evaluated under different acoustic conditions using an extensive database that has already taken place in the literature. During the testing of the analyzed VADs, different input noise speech signals with environmental background noises between [15-0dB] such as restaurant, car, street, or station were tested. Tests were carried out using objective test measurement methods and the detection accuracy rate of each VAD method was measured. The results showed that each method gave different endurance performance in adverse environmental conditions.Article Architectural Design - Structural System Conformity Problems Encountered in the Design and Application Processes of Stick Aluminium Curtain Wall Systems in Turkey(Gazi Univ, Fac Engineering Architecture, 2022) Ozmen, Cengiz; Saban, MugeStick aluminium curtain wall (SACW) systems are common curtain wall systems in Turkey. These sytems offer many advantages including architectural variation, modular design, ease of production and assembly. Beside their architectural properties SACW systems create significant load effects on structural systems. These load effects include lateral loads such as seismic and wind loads as well as static vertical loads. This load transfer is not one way. The vertical and lateral displacements of building structures also act on curtain walls. Healthy load transfer between the SACW and the building depends on architectural decisions during the design and construction process. Due to their wide use SACW systems are prone to architectural mistakes. These mistakes often represent themselves at latter stages of the construction and require solutions which will affect the architectural characteristics and structural behavior of buildings. This study focuses on SACW design and construction processes to find the effects of architectural decisions on curtain wall behavior. Case studies that include architectural design mistakes are selected to classify and study the reasons and the solutions of these mistakes. The importance of cooperation between all the stakeholders including the architects and engineers is emphasized for the prevention of these mistakes.Article Citation - WoS: 12Citation - Scopus: 19Artificial Intelligence Applications in Earthquake Resistant Architectural Design: Determination of Irregular Structural Systems With Deep Learning and Imageai Method(Gazi Univ, Fac Engineering Architecture, 2020) Bingol, Kaan; Akan, Asli Er; Ormecioglu, Hilal Tugba; Er, ArzuAlthough the architectural design process is carried out with the collaboration of experts who are experienced in many different areas from the main preferences to the detailing stage, the major decisions such as plan organization, mass design etc. are taken by the architect. Computer Aided Design (CAD) programs are generally effective after the major decisions of the design are taken. For this reason, it is common for the main decisions, taken during the design process, to be changed during the analysis of the structural system. In order to prevent this, in the early stages of architectural design, earthquake system awareness and structural system design should be included as an design input; as, the failure of the structural system which did not considered well in the architectural design phase leads to unexpected revisions in the implementation project phase and thus leads to serious losses in both time and cost. The aim of this study is to create an Irregularity Control Assistant (IC Assitant) that can provide architects general information about the appropriateness of structural system decisions to earthquake regulations in the early stages of design process by using the deep learning and image processing methods. In this way, correct decisions will be made in the early stages of the design and unexpected revisions that may occur during the implementation project phase will be prevented.