Mekatronik Mühendisliği Bölümü Yayın Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/255
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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: 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.Conference Object Fluorescent On-Chip Imager by Using a Tunable Absorption Filter(Ieee, 2017) Arpali, Caglar; Yıldırım, Ender; Yildirim, Ender; Arpali, Çağlar; Arpali, Serap Altay; Arpali, Serap; Makine Mühendisliği; Mekatronik Mühendisliği; Elektronik ve Haberleşme MühendisliğiConference Object High-Throughput Screening of Blood Samples Based on Structured Illumination On-Chip Imaging(IEEE, 2013) Arpali, Serap; Arpali, S.A.; Arpali, Çağlar; Arpali, C.; Coskun, A.F.; Chiang, H.-H.; Ozcan, A.; Mekatronik Mühendisliği; Elektronik ve Haberleşme MühendisliğiWe demonstrate a high-throughput fluorescent on-chip imaging platform, using structured illumination that can rapidly screen large volumes of scattering media such as undiluted whole blood samples (e.g., ~ 0.3-0.7 mL) for detection of fluorescent micro-objects at low concentrations (e.g.,≤50-100 particles/mL). This imaging modality might especially be useful for rare cell applications involving whole blood samples, such as detection of circulating tumor cells. © 2013 OSA.Conference Object Citation - Scopus: 2An Optimization Model To Coordinate Scheduling and Controling in Projects: Case With Instantaneous Control Constraints(National Technical University of Athens, 2014) Schmıdt, Klaus Werner; Hazir, Ö.; Schmidt, K.W.; Eryilmaz, U.; Mekatronik MühendisliğiToday, many enterprises in different industries take part in various projects, and organizational performances depend more and more on project performances. In order to maximize performance, effective management of project functions is crucial. In this regard, we focus on scheduling and control functions and their relation. Characteristics of data sharing among them and possible integration strategies are theoretically investigated. A model base for a decision support framework that accounts for these interdependencies and supports managers is developed. To solve the formulated integrated project scheduling and control problem, a tabu search algorithm is combined with optimal control techniques. As a result, a project schedule as well as the means and timing of interventions are determined such that the project cost is minimized. The obtained results are supported by computational experiments. Integrated models and algorithms to be developed aim to fill an important theoretical gap in project management.Conference Object Controller Design for Cacc With Time-Varying Communication Delays(Ieee, 2023) Soysal, Gokhan; Schmidt, Klaus Werner; Bingol, HilalCooperative Adaptive Cruise Control (CACC) aims at the safe and comfortable travel of vehicles at short distances in the form of platoons. Hereby, it is generally desired to attenuate disturbances along vehicles in a platoon, which is captured by different string stability conditions. In this paper, we focus on L-infinity string stability. This condition ensures reducing the magnitude of the acceleration signal along the platoon, which helps to avoid actuator saturation and increases driving comfort. Since the performance of CACC is adversely affected by time-varying communication and actuator delays, we develop the first controller design method for L-infinity-string stability, combining the Lyapunov-Krasovskii method and our custom bisection algorithm. Simulation experiments demonstrate the effectiveness of our method.Conference Object Comprehensive Comparison of Various Machine Learning Algorithms for Rf Fingerprints Classification(Institute of Electrical and Electronics Engineers Inc., 2023) Ergezer, H.; Gundogan, B.In these days, the use of drones has become quite common. Remote controls can do the control of these drones with RF signals. It is important to prevent security vulnerabilities caused by using drones in our daily lives. A complex dataset was created by extracting the characteristics of the RF signals and preprocessing them. To solve this complex data set and problem, the application of models including Support Vector Machine (SVM), Random Forest, Decision Tree, Gradient Boosting, XGBoost and Neural Network (NN) models, including various ML models and comparison of optimization studies of these applied models are examined in this article. In addition, a wide range of studies was carried out to compare ML models, including comparison metrics such as Accuracy, Precision, Recall, Mean Squared Error (MSE), F1 Score, $R^{2}$ and Training Time. In line with these results, the highest score was obtained in the $\mathrm{R}^{2}$ comparison metric (97%) in the Neural Network (NN). Compared to the others, the results of Neural Network (NN) were more successful, but the Training Time (245 sec) in the Neural Network (NN) method is by far more than the other ML methods, which shows us that the NN method requires a very high computing process. As a result of the comparison, another outstanding Ensemble-based ML method is Decision Tree. This is because besides the very low Training Time $(5\sec)$, it has managed to be the 2nd ML algorithm with the highest $\mathrm{R}^{2}$ score (96%). Apart from these, among other ML methods, SVM performed slightly less well $(\mathrm{R}^{2}$ 91%) in solving this complex problem. The advanced Gradient Method (95%) and XGBoost (96%), which also have the Ensemble structure, showed a head-to-head performance regarding $\mathrm{R}^{2}$ scores. However, XGBoost (30 sec) has a very short Training Time compared to Gradient Boosting (180 sec). As a result, the approach of each ML method to solving the complex problem differed from each other, and the success rates and Training Time also differed equally. The most important work to be done here is to choose which ML method you want to achieve according to the limited system in hand and the performance-accuracy dilemma. © 2023 IEEE.Article Citation - WoS: 4Citation - Scopus: 4String Stability Under Actuator Saturation on Straight Level Roads: Sufficient Conditions and Optimal Trajectory Generation(Ieee-inst Electrical Electronics Engineers inc, 2022) Bingol, Hilal; Schmidt, Klaus WernerThe heterogeneity of vehicles is an important factor when realizing cooperative adaptive cruise control (CACC) in practice. Specifically, it has to be considered that platoons generally consist of vehicles with both different dynamic properties and actuator limits on the engine and braking force, which is expected to have a negative impact on important properties such as string stability. Accordingly, the subject of this paper is the preservation of string stability for CACC in heterogeneous vehicle strings with potential actuator saturation. To this end, the paper formulates a velocity-dependent force bound that enables the derivation of sufficient conditions for preserving string stability during velocity changes of heterogeneous platoons. These conditions are then used for the analytical computation of trajectories for time-optimal velocity changes. The formal results of the paper are supported by an illustrative simulation study.Article Citation - WoS: 7Citation - Scopus: 6Dynamic Flat-Topped Laser Beam Shaping Method Using Mixed Region Amplitude Freedom Algorithm(Springer Heidelberg, 2022) Arpali, Caglar; Arpali, Serap Altay; Altemimi, Mohammed Fawzi; Alsaka, Dina YaqoobA dynamic beam shaping method is proposed for the generation of flat-top beams (FTBs) in the far field. Using the mixed-region amplitude freedom algorithm, this new method is used to design the required phase distribution encoded on a spatial light modulator for the generation of FTB profiles. The characteristics of these new beam shaping methods are used as beam parameters, such as the laser beam size, the beam intensity of square FTBs, and the root-mean-square error (RMSE). Using our proposed method, the theoretical performance of beam intensity shaping is improved to an RMSE < 0.02 with a minimum number of iterations of phase reconstruction. Using the phase hologram of dynamic beam shaping, theoretical and experimental comparisons of edge steepness and plateau uniformity were established for the square FTBs of variable beam sizes. It is shown that the dynamic beam shaping of FTBs can produce high intensity uniformity in the plateau region with steep edges, which makes it an effective tool, especially for laser machining applications.Article Citation - WoS: 2Citation - Scopus: 2Development of Air-To Engagement Analysis Model of Fighter Aircrafts(Gazi Univ, Fac Engineering Architecture, 2022) Bektas, Almila; Ergezer, Halit; Erdogan, SinemIn operational analysis studies; it is possible to model and simulate at an engineering level, engagement level, task level and campaign forces level. In this study, modelling and simulation studies are performed in engagement-level allowing the analysis of air-to-ground engagement effectiveness of fighter aircraft according to the operational environment. The operating environment of the combat aircraft, which provides survivability analysis based on low visibility and electronic mixing capabilities, is created. The search radar and tracking radar models for ground-to-air threats have been designed in accordance with the engagement level. The dynamic model of the fighter aircraft and the ground-to-air missile have been modelled using pseudo 5 degree-of-freedom. Modelling has been carried out to allow the use of changes in the Radar Crosssectional Area (RCS), which is one of the most important factors affecting the survivability of the aircraft, with respect to azimuth and elevation angles. The Radio Frequency (RF) jamming capability of the fighter aircraft has also been modelled in accordance with the engagement level. The results of the generic scenarios for the analysis of the effect of these models' parameters on the survivability of fighter aircraft have been presented.