Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collections

Permanent URI for this collectionhttps://hdl.handle.net/20.500.13091/3

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Citation - Scopus: 2
Adaptation Analysis of Produced 3d Models From Uav-Slam and Uav-Tls Data Combinations
(Mersin University, 2023) Erdal, Kasım; Makineci, Hasan Bilgehan
Photogrammetric techniques are widely used to represent the characteristics of historical buildings in the digital environment in the closest way to reality. Terrestrial photogrammetric methods have needed different alternatives in recent years to produce 3D models that offer high reality. In recent years, producing point data with the Terrestrial Laser Scanner (TLS), Unmanned Aerial Vehicles (UAV) images, and alternative methods such as the Simultaneous Localization and Mapping (SLAM) algorithm has become popular. Aligning point data from different approaches and making 3D models create new problems. Primarily, it is necessary to investigate the operations performed manually by the operator over time. Also, it is needed to explore the integration of automatic algorithms such as Iterative Closest Point (ICP) in terms of accuracy. In this research, point data of the Dokuz Historical Bridge was produced using different aligning techniques manually and automatically with the ICP algorithm. The assessment has been done from the results of combined point data over time and accuracy. In both UAV-TLS and UAV-SLAM aligning procedures, spatial accuracy was determined as 2.8cm and 4cm, respectively, in the operations performed by the operator and 46cm and 12cm in the procedures performed automatically by ICP. As a result, it was determined that the operators combined produced better findings, especially in research including coordinate transform. © Author(s) 2023.
Citation - WoS: 1
Citation - Scopus: 2
Adaptive State Feedback Control Method Based on Recursive Least Squares
(Kauno Technologijos Universitetas, 2022) Levent, Mehmet Latif; Aydoğdu, Ömer
This study revealed an adaptive state feedback control method based on recursive least squares (RLS) that is introduced for a time-varying system to work with high efficiency. Firstly, a system identification block was created that gives the mathematical model of the time-varying system using the input/output data packets of the controller system. Thanks to this block, the system is constantly monitored to update the parameters of the system, which change over time. Linear quadratic regulator (LQR) is renewed according to these updated parameters, and self-adjustment of the system is provided according to the changed system parameters. The Matlab/Simulink state-space model of the variable loaded servo (VLS) system module was obtained for the simulation experiments in this study; then the system was controlled. Moreover, experiments were carried out on the servo control experimental equipment of the virtual simulation laboratories (VSIMLABS). The effectiveness of the proposed new method was observed taking the performance indexes as a reference to obtain the results of the practical application of the proposed method. Regarding the analysis of simulation and experimental results, the proposed approach minimizes the load effect and noise and the system works at high efficiency. © 2022 Kauno Technologijos Universitetas. All rights reserved.
Citation - WoS: 3
Citation - Scopus: 2
Adaptive Traffic Management Model for Signalised Intersections
(Kauno Technologijos Universitetas, 2024) Yalcinli, F.; Akdemir, B.; Durdu, A.
As population increases, one of the factors affecting life is traffic. Efficient traffic management has a direct positive impact on issues such as time, carbon dioxide emissions, and fuel consumption. Today, an important parameter under the heading of traffic is the signalling systems for intersections, which are operated with fixed-time, semi-actuated, fully actuated, and fully adaptive control methods. In this study, an adaptive traffic management model is developed for signalised intersections. The adaptive traffic management model developed includes phase extension with minimum and maximum time intervals dependent on density and phase skip features. Additionally, the most distinctive feature of the model is its flexible phase structure rather than a sequential phase. The Heybe intersection, located within the boundaries of Antalya province, is modelled one-to-one in the simulation of urban mobility (SUMO) simulation programme with real intersection data. The developed adaptive traffic management model is applied to the Heybe intersection, and the effects of the model are revealed. Improvements obtained from the SUMO simulation programme were verified through visual inspection, and high-accuracy results were determined. As a result of the studies, it was found that the application of the adaptive traffic management model developed at Heybe intersection, which has approximately 50,000 vehicles passing daily, resulted in a 27.2% improvement in the average delay per vehicle parameter, a 32.4% improvement in the average waiting time per vehicle parameter, and a 16.7 % improvement in the average speed per vehicle parameter. © 2024 Kauno Technologijos Universitetas. All rights reserved.
Citation - WoS: 2
Citation - Scopus: 2
Adrenal Lesion Classification With Abdomen Caps and the Effect of Roi Size
(Springer, 2023) Solak, Ahmet; Ceylan, Rahime; Bozkurt, Mustafa Alper; Cebeci, Hakan; Koplay, Mustafa
Accurate classification of adrenal lesions on magnetic resonance (MR) images are very important for diagnosis and treatment planning. The detection and classification of lesions in medical imaging heavily rely on several key factors, including the specialist's level of experience, work intensity, and fatigue of the clinician. These factors are critical determinants of the accuracy and effectiveness of the diagnostic process, which in turn has a direct impact on patient health outcomes. With the spread of artificial intelligence, the use of computer-aided diagnosis (CAD) systems in disease diagnosis has also increased. In this study, adrenal lesion classification was performed using deep learning on MR images. The data set used was obtained from the Department of Radiology, Faculty of Medicine, Selcuk University, and all adrenal lesions were identified and reviewed in consensus by two radiologists experienced with abdominal MR. Studies were carried out on two different data sets created by T1- and T2-weighted MR images. The data set consisted of 112 benign and 10 malignant lesions for each mode. Experiments were performed with regions of interest (ROIs) of different sizes to increase the working performance. Thus, the effect of the selected ROI size on the classification performance was assessed. In addition, instead of the convolutional neural network (CNN) models used in deep learning, a unique classification model structure called Abdomen Caps was proposed. When the data sets used in classification studies are manually separated for training, validation, and testing, different results are obtained with different data sets for each stage. To eliminate this imbalance, tenfold cross-validation was used in this study. The best results obtained were 0.982, 0.999, 0.969, 0.983, 0.998, and 0.964 for accuracy, precision, recall, F1-score, area under the curve (AUC) score, and kappa score, respectively.
Citation - Scopus: 1
Adrenal Tumor Segmentation on U-Net: a Study About Effect of Different Parameters in Deep Learning
(World Scientific Publ Co Pte Ltd, 2023) Solak, Ahmet; Ceylan, Rahime; Bozkurt, Mustafa Alper; Cebeci, Hakan; Koplay, Mustafa
Adrenal lesions refer to abnormalities or growths that occur in the adrenal glands, which are located on top of each kidney. These lesions can be benign or malignant and can affect the function of the adrenal glands. This paper presents a study on adrenal tumor segmentation using a modified U-Net model with various parameter selection strategies. The study investigates the effect of fine-tuning parameters, including k-fold values and batch sizes, on segmentation performance. Additionally, the study evaluates the effectiveness of different preprocessing techniques, such as Discrete Wavelet Transform (DWT), Contrast Limited Adaptive Histogram Equalization (CLAHE), and Image Fusion, in enhancing segmentation accuracy. The results show that the proposed model outperforms the original U-Net model, achieving the highest scores for Dice, Jaccard, sensitivity, and specificity scores of 0.631, 0.533, 0.579, and 0.998, respectively, on the T1-weighted dataset with DWT applied. These results highlight the importance of parameter selection and preprocessing techniques in improving the accuracy of adrenal tumor segmentation using deep learning.
Citation - WoS: 6
Citation - Scopus: 9
Ağaç-tohum Algoritmasının Cuda Destekli Grafik İşlem Birimi Üzerinde Paralel Uygulaması
(2018) Çınar, Ahmet Cevahir; Kıran, Mustafa Servet
Son yıllarda toplanan verinin artmasıyla birlikte verimli hesaplama yöntemlerinin de geliştirilmesi ihtiyacı artmaktadır. Çoğunlukla gerçek dünya problemlerinin zor olması sebebiyle optimal çözümü garanti etmese dahi makul zamanda yakın optimal çözümü garanti edebilen sürü zekâsı veya evrimsel hesaplama yöntemlerine olan ilgi de artmaktadır. Diğer bir açıdan seri hesaplama yöntemlerinde verinin veya işlemin paralelleştirilebileceği durumlarda paralel algoritmaların da geliştirilmesi ihtiyacı ortaya çıkmıştır. Bu çalışmada literatüre son yıllarda kazandırılmış olan popülasyon tabanlı ağaç-tohum algoritması ele alınmış ve CUDA platformu içerisinde paralel versiyonu geliştirilmiştir. Algoritmanın paralel versiyonunun performansı kıyas fonksiyonları üzerinde analiz edilmiş ve seri versiyonunun performansı ile karşılaştırılmıştır. Kıyas fonksiyonlarında problem boyutluluğu 10 olarak alınmış ve farklı popülasyon ve blok sayıları altında performans analizi yapılmıştır. Deneysel çalışmalar algoritmanın paralel versiyonunun algoritmanın seri sürümüne göre bazı problemler için 184,65 kata performans artışı sağladığı görülmüştür.
Aggloflotation of Bituminous Coal in a New Designed Cell
(Taylor & Francis Inc, 2025) Uslu, Nihat Yusuf; Duzyol, Selma
This study investigated the enrichment of high-ash bituminous coal by aggloflotation technique implemented within a new designed experimental cell. At the same time, this paper aimed to introduce the newly designed aggloflotation cell. This novel cell uniquely integrates the agglomeration and flotation processes into a single, unified unit, thereby simplifying the overall processing sequence. A coal sample, sourced from the Zonguldak & Ccedil;atala & gbreve;z & imath; coal preparation plant, was subjected to a series of tests under varied operational conditions including pH levels, agglomeration time, binder dosage, mixing speed, frother dosage, and dispersant. The performance of the aggloflotation process was evaluated by examining key metrics such as the concentrate's ash content, weight yield, and the combustible recovery. Notably, the experimental outcomes demonstrated that the new designed cell was efficient in processing ultra-fine bituminous coal in a single-stage operation. The process reduced the agglomeration time from 30 minute to just 5 minute, indicating substantial potential for both time and energy savings. Preliminary observations indicate that integrating both processes in one cell may also simplify process control. The outcomes suggest that this experimental setup represents a viable option for coal enrichment, inviting further investigation to determine its potential benefits.
Citation - Scopus: 2
Air Quality Status in Konya City Centre, Konya, Turkey During Pandemic Covid-19
(Institute of Physics, 2022) Yahaya, N. Z.; Jalaludin, J.; Toros, H.; Dursun, S.
High developed industry regions, provincial centers with a heavy traffic and dense populations with cold winters, using low-quality fossil fuel consumption have an effect on quality of life especially for people with respiratory diseases. The air quality data gathered from air monitoring stations for the City Center of Konya, Turkey were analysed statistically during the period when curfew due to the Covid-19 pandemic in 2020. The restrictions that cause the reduction of vehicle exhaust emissions, which are important factors in the formation of some air pollutants, are thought to be effective in improving the air quality as well as meteorological conditions are effective on the days when the air quality is analysed. It is thought that the reduction in HC, NOx, CO and PM emissions, which can be evaluated as exhaust emissions, will be an effective factor due to the restrictions of Covid-19 pandemic. Comparing between the 2019 and 2020 MCO data, we identified that most of the gases decreased with NO2 (-24 ?g/m3), SO2 (-24 ?g/m3), CO (-37 ?g/m3) and an increment of O3 of +50 ?g/m3 which indicates that the MCO and restricted of movement were give an impact to air quality levels in Konya City. The increase in O3 values were found by the existing of the sun rays in the atmosphere with the formation of O3 during the clean air period. © Published under licence by IOP Publishing Ltd.
Airborne Gravity Data Reconstruction Strategies for Geoid Optimization in Peninsular Malaysia
(Association for Geoinformation Technology, 2025) Zamri, A.N.M.; Pa’suya, M.F.; Din, A.H.M.; Abbak, R.A.; Ali, T.A.T.; Talib, N.; Othman, N.A.
Geoid height is essential for precise height determination, particularly in surveying and geodetic applications. Airborne gravity data substantially improve geoid models, especially over regions with complex terrain where terrestrial coverage is limited. However, since airborne data are acquired at flight altitude, they require downward continuation to the geoid surface which an inherently unstable process. Despite ongoing advancements, the most effective strategy for combining and gridding gravity data, particularly airborne measurements, remains a topic of research. This study evaluates two downward continuation strategies to assess their influence on geoid accuracy. The first strategy applies downward continuation to airborne data simultaneously with terrestrial and marine data, incorporating a range of buffer distances (0 km, 1 km, 5 km, and 10 km) to examine their effect on model performance. The second strategy involves performing downward continuation on airborne data independently before merging with other datasets. Numerical results indicate the Root Mean Square Error (RMSE) values of 0.044 m for the first strategy and 0.045 m for the second, with a marginal difference of 0.001 m. Although the difference appears minor, even marginal improvements can be pivotal in high-precision geoid modelling particularly in localized regions where complex topography or sparse data coverage may magnify subtle errors. Such refinements are essential to advancing the long-term goal of achieving geoid accuracy at the 1 cm level for Peninsular Malaysia. © Geoinformatics International.
Citation - WoS: 14
Citation - Scopus: 13
All-Dry Hydrophobic Functionalization of Paper Surfaces for Efficient Transfer of Cvd Graphene
(WILEY-V C H VERLAG GMBH, 2019) Çıtak, Emre; İstanbullu, Bilal; Şakalak, Hüseyin; Gürsoy, Mehmet; Karaman, Mustafa
In this study, the successful transfer of chemical vapor deposition (CVD)-grown graphene on an ordinary printing paper surface is demonstrated. Pristine paper is not a suitable substrate for graphene transfer because of its fragile and hydrophilic nature against the chemicals used during the transfer process. Two different fluoroalkyl polymers, namely poly(hexafluorobutyl acrylate) (PHFBA) and poly(perfluorodecyl acrylate) (PPFDA) are coated on paper surfaces by an initiated CVD (iCVD) technique to make the paper surfaces hydrophobic. Hydrophobicity is found to be an important factor in order for the graphene to be transferred onto the paper substrate. Although surfaces coated with PPFDA possess better hydrophobicity owing to their longer perfluoroalkyl group and higher roughness, the graphene transfer is found to be more successful on a PHFBA-coated surface. A thin film of PHFBA on the paper surface acts as a prime layer for effective and defect-free transfer of graphene and makes the paper surface ideal and robust during the graphene transfer process. The as-transferred graphene layer on the PHFBA-coated paper surface shows high conductivity values, even after repeated folding and flattening cycles.
Citation - WoS: 23
Citation - Scopus: 24
All-Dry Patterning Method To Fabricate Hydrophilic/Hydrophobic Surface for Fog Harvesting
(SPRINGER, 2020) Gürsoy, Mehmet
Inspired by natural creatures that live in the arid climate, fog harvesting can be an efficient approach to overcome freshwater scarcity. Fog harvesting ability of the creatures is mainly based on wettability differences of their surfaces. In this study, inspired by creatures that have hydrophilic regions surrounded by hydrophobic areas, a novel all-dry patterning method was applied to fabricate hydrophilic/hydrophobic patterned surfaces for fog harvesting. For this purpose, patterned surfaces were produced using plasma-enhanced chemical vapor deposition (PECVD) method with the help of a commercial magnet and iron powders. The idea behind the use of the magnetic field during PECVD deposition is to hold light iron particles on the substrate under the vacuum environment for masking substrate surface. For the first time, the magnetic field was used to fabricate patterned surfaces in vapor-phase polymerization. Ordinary glass slides were successfully transformed into hydrophilic/hydrophobic patterned glasses. The obtained results showed that the combination of hydrophobic and hydrophilic regions improved the fog harvesting performance.
Alteration Mineralogy and Fluid Inclusion Microthermometry of the Hes-Daba Area in Gagade, Republic of Djibouti
(Murat Yakar, 2025) Bayram, A.F.; Hassanleh Hassan, M.
This study focuses on fluid inclusions from the Hes-Daba area. Microthermometric measurements were conducted on quartz collected from surface veins that hosted inclusions in two phases: liquid and vapor. The mean homogenization temperature ranged from 150 °C to 367 °C and the melting point of ice ranged from −0.05 °C to −1.14 °C, indicating that the inclusion solutions consisted of 0.1 to 1.9 eq. wt% NaCl. The thermal history and thermal structure were evaluated to estimate the formation temperature. Selected samples were analyzed via x-ray diffraction to provide direct data on geothermal reservoirs; this was necessary because geothermal fluids, through their interactions, can alter the composition and properties of rocks. The main alteration minerals were quartz, calcite, alunite, epidote, hematite, illite, smectite, and chlorite. Therefore, the clay constituted a transition to a hightemperature environment, as evidenced by high temperature hydrothermal alteration minerals such as quartz (>180 °C) and epidote (~250 °C). © 2025, Murat Yakar. All rights reserved.
Citation - WoS: 8
Citation - Scopus: 9
Amplifying the Dielectric Constant of Shellac by Incorporating Natural Clays for Organic Field Effect Transistors (ofets)
(TUBITAK, 2023) Kim, S.; Yumuşak, Ç.; Irimia, C.V.; Bednorz, M.; Yenel, E.; Kuş, M.; Sariçiftçi, N.S.
We demonstrate in this work the practical use of uniform mixtures of a bioresin shellac and four natural clays, i.e. montmorillonite, sepiolite, halloysite and vermiculate as dielectrics in organic field effect transistors (OFETs). We present a thorough characterization of their processability and film forming characteristic, surface characterization, elaborate dielectric investigation and the fabrication of field effect transistors with two classic organic semiconductors, i.e. pentacene and fullerene C60. We show that low operating voltage of approximately 4 V is possible for all the OFETs using several combinations of clays and shellac. The capacitance measurements show an improvement of the dielectric constant of shellac by a factor of 2, to values in excess of 7 in the uniform mixtures of sepiolite and montmorillonite with this bioresin. © TÜBİTAK.
Analysis and Design of a Permanent Magnet Linear Synchronous Motor Based on Inductance Calculation
(Polska Akad Nauk, Polish Acad Sciences, 2025) Yucel, Enes; Mutluer, Mumtaz; Cunkas, Mehmet
This paper presents a comprehensive design and analysis methodology for a Permanent Magnet Linear Synchronous Motor (PMLSM), with a focus on evaluating different inductance modeling approaches. The motor design begins with analytical dimensioning based on defined design parameters. A two-dimensional finite element analysis follows this in ANSYS Maxwell to verify magnetic saturation, back-EMF, flux linkage, and electromagnetic performance under full load conditions. The inductance parameters are calculated using both conventional and look-up table (LUT) based models. In the conventional model, seven different methods are tested under static and dynamic conditions, as well as in non-salient and salient scenarios, and their results are compared. In the LUT model, current-dependent inductance values are extracted from flux linkage maps. The motor designed in Maxwell, along with the calculated inductance data, is integrated into a dynamic cooperative simulation (co-sim) model controlled by an inverter in Simplorer to analyze the thrust force. The results show that the LUT model provides outputs that are closer to the co-sim reference than the traditional model. Furthermore, performance curves based on the Maximum Torque Per Ampere strategy are generated, and the force-speed and power-speed characteristics derived from both inductance models are compared. The findings emphasize the importance of accurate inductance modeling in capturing the actual electromagnetic behaviour of PMLSM under dynamic operating conditions.
Citation - WoS: 1
Citation - Scopus: 1
Analysis of Fluid Forces Impacting on the Impeller of a Mixed Flow Blood Pump With Computational Fluid Dynamics
(Sage Publications Ltd, 2024) Diallo, Abdoulaye Billo; Cinar, Hasan; Yapici, Rafet
This study presents four different impeller designs to compare hydrodynamic forces. Numerical simulation studies are performed via computational fluid dynamics to specify and investigate the hydraulic forces impacting the impeller of the mixed-flow blood pump with a volute. The design point of this pump is that the flow rate is 5 L/min, the rotational speed is 8000 rpm, and the manometric head is 100 mmHg. The designed impellers are placed in the same volute and simulation studies are performed with the same mesh size (17.3 million cells) of the pumps. The simulation studies have been conducted in setting 1050 kg/m3 blood density, 35 cP fluid viscosity, and SST-k omega turbulence model. Additionally, this study examines the changes in hydraulic forces and hydraulic efficiency with fluid viscosity. As a result of experimental simulation studies, the highest hydraulic efficiencies of 40.87% and 39.5% are achieved in the case of the shaftless-grooveless and shafted-grooveless impeller, respectively. The maximum axial forces are obtained from the pump with the shaftless-grooveless impeller. Whereas radial forces, maximum values are calculated in the pump with the shaftless-outer groove impeller for all flow rates. Finally, the wall shear stresses, which are important for blood pump designs, are evaluated and the maximum value of 227 Pa is observed in the pump impeller with a shaftless-grooved.
Citation - WoS: 1
Citation - Scopus: 1
Analysis of Short-Term Sentinel-1 Data Using the Dinsar Method for Monitoring Displacement Following the Earthquakes of 6 and 20 February in Hatay City
(Ist Nazionale Di Oceanografia E Di Geofisica, 2024) Doganalp, S.; Cokuner, B.; Makineci, H. B.
The Eastern Anatolia Fault Zone (EAFZ) has caused destructive earthquakes. Kahramanmara and Hatay, located on the EAFZ, were hit by devastating earthquakes with magnitudes of 7.7, 7.6, and 6.3, respectively, in February 2023. A tectonic chain of disasters was seen in Hatay in a short time, first on 6 February 2023, with earthquakes centred in Kahramanmara and the subsequent intense earthquake series, and lastly on 20 February 2023, with the Hatay earthquake centred in the Yayladag district. The lithological characteristics of the units in the region increased the destructive effects of the earthquakes. In addition, the location of the study area, where the EAFZ and the Death Sea Fault Zone are close to each other, increases the importance of research. This study aims to monitor the ground displacements caused by the earthquakes in Hatay. Sentinel1A Synthetic Aperture Radar data was acquired on 29 January, and 10 and 22 February, and the Differential Interferometry Synthetic Aperture Radar method was applied. In addition, the elevation change was determined by using two-month global navigation satellite system data from the Continuously Operating Reference Station points (HAT2 and ONIY) in the study area. Thus, considering regional tectonics, ground movements resulting from the earthquakes on 6 and 20 February were identified and examined using geologic, geodesic, and remote sensing techniques.
Citation - WoS: 7
Citation - Scopus: 7
An Analytical Study About the Use of Steel Plate Shear Walls To Improve Lateral Rigidity of Reinforced Concrete Framed Structures
(LATIN AMER J SOLIDS STRUCTURES, 2020) Korkmaz, Serra Zerrin
Steel plate shear walls are becoming popular for steel structures. In this study, the use of Steel Plate Shear Walls (SPSW) was discussed to increase the horizontal stiffness of reinforced concrete structures. It was aimed to fix the SPSW elements to the exterior of the building. ABAQUS models of SPSW applied 2D frame samples, which were tested in a previous experimental study, were created. Experimental and analytical horizontal load-top displacement curves were found to be in good agreement. In the study, ABAQUS models of a 6-story and 3D reinforced concrete building were also created. In models, SPSW elements were placed at the exterior of the building. The load capacities of the reinforced and non-reinforced building models were compared. The steel sheet thickness and the number of frame openings at which the SPSW element was placed were considered as the variable parameters.
Application of Fuzzy Logic Control for Enhanced Speed Control and Efficiency in PMSM Drives Using FOC and SVPWM
(IOP Publishing Ltd, 2025) Oztok, Mahmut Furkan; Dursun, Emre Hasan
PMSMs (Permanent Magnet Synchronous Motors) are favored in industrial systems requiring fast dynamic response and precision, thanks to their high efficiency and torque-to-inertia ratio. To fully leverage these motors, advanced control techniques like Field-Oriented Control (FOC) are essential, as they decouple torque and flux. However, traditional FOC systems often use PI controllers, which suffer from limited adaptability and challenging tuning processes, especially in applications demanding quick responses. To overcome these limitations, the study compared fuzzy logic-based speed control strategies. Three control structures were modelled in MATLAB/Simulink, integrating SVPWM for enhanced performance: traditional FOC with PI controller, FOC with single-input Fuzzy Logic Controller (FLC), and FOC with two-input FLC (FLC2). The simulation results clearly demonstrated FLC2's superior performance, achieving only 0.53% overshoot and a 0.08-second settling time. Quantitative metrics like IAE, ITAE, and ISE further validated FLC2's superiority over conventional control structures. These findings prove that, particularly the two-input FLC, offers a robust and high-performance alternative to traditional PI control in industrial automation, electric vehicles, and energy-efficient motor applications. With its simplicity, adaptability, and improved control performance, FLCs can play a significant role in next-generation smart motor drive technologies.
Citation - Scopus: 3
An Application of the Bees Algorithm To Pulsating Hydroforming
(Springer Nature, 2023) Öztürk, O.; Şen, M.A.; Kalyoncu, M.; Halkacı, H.S.
Pulsating hydroforming is a sheet forming process proposed in the last decade. The numerical simulation of this process requires biaxial stress–strain curves which can be obtained by performing a pulsating hydraulic bulge test. In this study, the input parameters of a pulsating hydraulic bulge test with titanium alloy sheets (Ti-6Al-4 V) are optimised using the Bees Algorithm (BA). The input parameters are amplitude and base pressure; bulge height (h) and minimum thickness (t) at dome apex are outputs. The mathematical modelling of h and the design of an objective function (J) are needed for optimisation. A second-degree polynomial equation is derived for h using curve fitting for three frequencies. Additionally, t is calculated depending on h. The objective function is designed for maximum normalised bulge height and minimum normalised thickness. The results show less thinning at the dome apex with a bulge height similar to that of the traditional monotonous method. Thus, a uniform thickness distribution, which is a critical quality indicator in hydroforming, is obtained with acceptable loss in bulge height. After optimisation, ?t (t-t0) is improved by approximately 9%. The bulge height increases by 15 and 13% in the best experimental case and the BA-optimised results, respectively. Consequently, the ductility of Ti-6Al-4 V sheet is increased, and the input parameters are optimised. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.
Citation - WoS: 1
Citation - Scopus: 5
An Application on the Use of Fuzzy Multi Criteria Decision Making Methods for Software Project Development Process Selection
(Gazi Univ, Fac Engineering Architecture, 2023) Yel, İbrahim; Baysal, Mehmet Emin
Software development projects are difficult to manage, as they involve complex business stages and the resources used are made up of real people. Along with the specifications of the projects, organizational variables and the competencies of the team members are among the factors that will directly affect the success of the project. It is thought that the success of software development projects will increase with the use of these three factors in the solution of the software development process method selection problem. In the management of software projects, different process methods are used, including Agile and Waterfall (Traditional) Methods. It is important to assign development teams to projects according to their abilities and to rank the projects among themselves. As a first step in this study, the weights of the criteria were determined using the fuzzy AHP. Then fuzzy WASPAS, fuzzy EDAS and Interval Neutrosophic Z Numbers (NZN) methods were used to rank projects and employees. According to the results of this research with sensitivity analysis, it has been determined that if the software development method decision is implemented, the number of defects and their solutions can be improved by 4.2%-6%, 5.8%-7.3% and 6.8%-9.7% when compared to the actual values of person-day values.

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