Mekatronik Mühendisliği Bölümü Yayın Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/255

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A comparison of iterative Fourier transform algorithms for image quality estimation
(2018) Alsaka, Dina Yaqoob; Arpali, Çağlar; Arpali, Serap Altay
A comparison was established between two iterative Fourier transform algorithms (IFTAs), such as the original Gerchberg–Saxton (GS) and the mixed-region amplitude freedom (MRAF) algorithms, for the hologram reconstruction of different target images through the full reference image quality estimation (IQE) and pixel homogeneity in the Fourier plane presented theoretically and experimentally. The comparison was applied depending upon both algorithms based on a computer-generated hologram (CGH) implemented utilizing a reflective phase-modulated liquid-crystal spatial light modulator (LC-SLM) to obtain the digital kinoform holograms of the desired intensity distributions. These digital holograms were applied to reconstruct the intensity patterns for 852 nm, which represents a laser beam source. The theoretical and experimental results of the reconstructed patterns obtained using the MRAF algorithm were found to be smoother and better than the patterns obtained using the GS algorithm. Unmodulated light beam (dc term) is removed from the reconstructed patterns attributed to digital kinoform holograms of MRAF algorithm as an alternative to the theoretical and experimental results without using any additional optic equipment at the light path. Moreover, this paper discussed the full reference objective quality estimations, such as mean square error (MSE), peak signal-to-noise ratio (PSNR), structural content (SC), normalized absolute error (NAE), normalized cross correlation (NK), and homogeneity of pixels, through the contrast (Cont) and inverse difference moment (IDM) for numerical and experimental results. According to the two desired intensity distributions processed theoretically and experimentally, the results of MRAF algorithm were found to be in the highly accurate recovered phase, the quality of image was enhanced, and the dc term was decreased. Image quality estimation of full reference objective relay on the feedback algorithms experimental attestation has not been implemented yet.
Computation of Reduced Diagnosers for the Fault Diagnosis of Discrete Event Systems
(2014) Kart, Bora Eser; Schmidt, Klaus
Many complex systems in different areas such as manufacturing, telecommunications or transportation can be modeled as discrete event systems (DES). In this paper, we consider the fault diagnosis for DES which is concerned with detecting fault occurrences in a DES within a bounded number of event occurrences by a diagnoser automaton. Hereby, such diagnoser is able to observe a subset of the system events and the maximum required number of event occurrences until a fault detection is denoted as the worst case detection delay (WCDD). The main contribution of the paper is an approach for reducing the number of required observations for fault diagnosis without increasing the WCDD. As a result, it is possible to determine a diagnoser with a small size which is essential in practical applications. We first develop an algorithm for computing the WCDD and then adapt an approach for the reduction of the observable event set in order to obtain a reduced diagnoser. The application of our method to a communication system example demonstrates its practicability.
Citation - WoS: 2
Citation - Scopus: 6
Controller Area Network With Priority Queues and Fifo Queues: Improved Schedulability Analysis and Message Set Extension
(inderscience Enterprises Ltd, 2016) Schmidt, Klaus Werner; Alkan, Burak; Schmidt, Ece Guran; Karani, Duygu Culum; Karakaya, Utku
Controller area network (CAN) enables communication of electronic control units (ECUs) via messages using priority-based arbitration, which requires the implementation of priority queues (PQs) in the ECU device driver. Nevertheless, it is possible that not all ECUs on a CAN support PQs but use FIFO queues (FQs) instead. In this case, the classical CAN scheduling model with PQs is not suitable for the computation of message worst-case responsetimes (WCRTs) that are essential for verifying the correct vehicle operation. This paper considers an existing scheduling model for CAN with both PQs and FQs. First, an improved algorithm for speeding up the WCRT computation is proposed. Second, the practical case where an existing CAN message set is extended by new messages is addressed. An original algorithm for assigning priorities to new messages while keeping the priority order of existing messages is developed. Both algorithms are evaluated by computational experiments.
Citation - WoS: 6
Citation - Scopus: 6
Design and Implementation of an Electrode Feed Rate Control System in the Electrochemical Drilling Process
(Springer Heidelberg, 2022) Cogun, Can; Ozerkan, Haci Bekir
The interelectrode gap distance control is essential for preventing short circuit and spark discharge occurrences in the machining gap and ensuring a constant distance between the tool electrode (shortly electrode) and the workpiece throughout the electrochemical drilling (ECD) process. In this study, a gap distance control system was designed and implemented in the constructed ECD machine tool. The gap distance control strategy was based on the machining current's discrete measurement (in microsecond intervals) and changing the gap distance according to a set current value by feeding the electrode towards the workpiece or retracting it during the ECD process. The small diameter deep hole ECD experiments were conducted using 0.5 mm diameter side insulated tubular rotational electrodes with through-hole electrolyte flushing to drill Hadfield and AISI 1040 steels. The experimental results demonstrated the success of the developed control system in ECD operations yielding uniform hole geometries and smooth hole surfaces. The use of the control system eliminated the undesirable formations of spark discharges and short circuit pulses.
Citation - Scopus: 2
Determination of Onset of Yield Due To Material Properties in a Heat Generating Two-Layered Compound Cylinder
(2013) Gulgec, M.; Ozturk, A.
In this theoretical study, based on Tresca's yield criterion and its associated flow rule, the elastic deformation of a centrally heated compound cylinder with fixed ends is investigated analytically by taking into consideration not only the geometrical but also the material parameters such as yield strength, modulus of elasticity, Poisson's ratio, thermal conductivity and coefficient of thermal expansion. These material parameters are assumed to be independent of the temperature. The compound cylinder is assumed to be very long such that axisymmetric condition exists. Both of the constituent materials of the two layers are supposed to be elastic-perfectly plastic materials. There is heat generation in the interior solid cylinder but no heat generation in the outer hollow cylinder. Both of the cylinders are assumed to be bounded perfectly at the interface. Elastic stress analysis is performed to prevent yield in the compound cylinder. © (2013) Trans Tech Publications, Switzerland.
Effect of the Material Properties on the Yielding of the Two-Layered Composite Cylinder with Free Ends
(2013) Yalçın, F.; Öztürk, A.; Gülgeç, M.
Citation - WoS: 1
Evaluation of Features Used in Electromyography Classification
(Ieee, 2021) Ergezer, Halit; Alguner, Ayber Eray
Classification of electromyography (EMG) signals using machine learning has been studied for a long time. Today, this classification is tried to be made more accurate, fast and applicable by using the methods developed. However, beside this effort, it is suspected that researchers are using features without taking into account the effects on the classification performance, but often by influence of other researches. From this point of view, the effects of some features used in studies published in recent years on classification performance were tested and the results obtained were shared. In the experiments performed using a common method support vector machine (SVM), it was found that increasing the number of features does not always provide an increase in performance, even in some cases, it causes a decrease in accuracy rates.
Citation - WoS: 191
Citation - Scopus: 228
An Experimental Investigation on the Impact Response of Composite Materials
(Pergamon-elsevier Science Ltd, 2012) Gulgec, Mufit; Evci, Celal
Due to the improved impact performance characteristics, composites are widely used in engineering and military applications to absorb the impact energy. Determination of impact response of composite materials provides the engineer and the manufacturer with critical knowledge to understand the failure criteria, initiation of the first failure and damage growth through the laminates. This study covers the investigation of impact damage growth and determination of Hertzian failure and maximum force thresholds in three different types of composites. Unidirectional E-Glass, woven E-Glass and woven Aramid composite samples with dimensions of 100 x 100 mm are subjected to low velocity impact with an instrumented impact test system. Rebound, on-set of perforation and perforation limits of composites are found out. Also, energy profile diagrams of both unidirectional and plain weave E-Glass composites are obtained. According to test results, woven composites are found to be superior to unidirectional composites in the protection limit of low velocity impact. It is also observed that damage growth in woven composites is restricted within a smaller area. Impact tests conclude that strength of the composite materials under dynamic loading increases considerably compared to static loading case as a result of strain rate sensitivity. (C) 2011 Elsevier Ltd. All rights reserved.
Citation - Scopus: 2
An Experimental Study of the Flexray Dynamic Segment
(IFAC Secretariat, 2010) Schmidt, K.; Schmidt, E.G.; Demirci, A.; Yürüklü, E.; Karakaya, U.
It is expected that the time-triggered FlexRay bus will replace the event-triggered Controller Area Network (CAN) for the high-speed in-vehicle communication in future automobiles. To this end, FlexRay provides a static segment for the transmission of periodic messages and a dynamic segment that is suitable for exchanging event-based (sporadic) messages. In this paper, we experimentally evaluate the operation of the FlexRay dynamic segment. In particular, we study how the maximum and average message delays are affected if the length of the dynamic segment, the message payload, the utilization of the dynamic segment and the priority assignment changes. Our experiments are carried out on a FlexRay network with 6 nodes. © 2010 IFAC.
Citation - Scopus: 1
Fuzzy Hybrid Systems Modeling With Application in Decision Making and Control
(2012) Boutalis, Y.; Moor, T.; Schmidt, K.
Hybrid Systems are systems containing both discrete event and continuous variable components. Many recent contributions address crisp situations, where ambiguity or subjectivity in the measured data is absent. In this paper, we propose Fuzzy Hybrid Systems to account for inaccurate measurements and uncertain dynamics. We present a strategy to determine the most appropriate control actions in a sampled data setting. The proposed approach is based on three basic steps that are performed in each sampling period. First, the current discrete fuzzy state of the system is determined by a sensor evaluation. Next, the future discrete fuzzy state is predicted for the possible control actions and the best action, in respect to desired continuous states, is selected. Finally, the decision is cross-evaluated by a limited horizon prediction of the continuous system variables. The proposed method is explained and demonstrated for a variation of the a well-known two-tank scenario. © 2012 IEEE.
High-Throughput Screening of Blood Samples Based on Structured Illumination On-Chip Imaging
(2013) Arpali, Serap; Arpali, S.A.; Arpali, Çağlar; Arpali, C.; Coskun, A.F.; Chiang, H.-H.; Ozcan, A.; Mekatronik Mühendisliği; Elektronik ve Haberleşme Mühendisliği
We 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.
The Implementation of Dynamic Distributed Real Time Industrial Communication Protocol (D 2rip)
(2012) Gözcü, A.K.; Turan, U.; Schmidt, E.G.; Schmidt, K.W.
Ethernet is a popular technology for industrial networking thanks to its low cost and high bandwidth. The current proposals to achieve real-time communication over Ethernet do not consider the determinism of the control applications resulting in inefficient use of bandwidth resources. We proposed a protocol stack architecture that works with standard Ethernet to address this problem. This paper describes the implementation of this architecture over Real-time Linux operating system and the first experiments to verify the operation. The implementation and performance of IEEE 1588 protocol which provides the required synchronization is also presented. © 2012 IEEE.
Lane Change Scheduling for Autonomous Vehicles
(2016) Atagoziyev, Maksat; Schmidt, Klaus W.; Schmidt, Ece G.
The subject of this paper is the coordination of lane changes of autonomous vehicles on a two-lane road segment before reaching a given critical position. We first develop an algorithm that performs a lane change of a single vehicle in the shortest possible time. This algorithm is then applied iteratively in order to handle all lane changes required on the considered road segment while guaranteeing traffic safety. Various example scenarios illustrate the functionality of our algorithm.
Optimal Message Scheduling for the Static Segment of Flexray
(IEEE, 2010) Schmidt, Klaus Werner; Schmidt, Ece G.
In this paper, we study the scheduling of periodic messages in the static segment of the FlexRay protocol. Our approach is based on two performance metrics. Similar to previous work, we seek to allocate a minimum number of frame IDs (FIDs) in the static segment. In addition, different from existing work, we want to minimize the message jitter, i.e., the deviation of the message transmission from the required periodicity. To this end, we first derive analytical expressions that quantify the FID allocation and the jitter, and then formulate a linear integer programming problem whose solution is the desired message schedule. An example illustrates our schedule optimization.
A Parametric Study on the Elastic-Plastic Deformation of a Centrally Heated Two-Layered Composite Cylinder With Free Ends
(Polish Acad Sciences inst Fundamental Technological Research, 2016) Yalcin, F.; Gülgeç, Müfit; Ozturk, A.; Gulgec, M.; Mekatronik Mühendisliği
In this paper, an elastic-plastic deformation of a centrally heated two-layered composite cylinder with free ends subjected to uniformly distributed internal energy generation within an inner cylinder is studied using Tresca's yield condition and its associated flow rule. Stress, strain and displacement distributions in the composite cylinder made of elastic-perfectly plastic material are derived 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 coefficient of thermal expansion. Yielding starts at the outer boundary or at the axis corresponding to an 'edge regime' of Tresca's prism in both cases. Propagations of the plastic regions are studied due to an increase of a heat generation.
Citation - WoS: 30
Citation - Scopus: 33
Sers-Based Ultrafast and Sensitive Detection of Luteinizing Hormone in Human Serum Using a Passive Microchip
(Elsevier Science Sa, 2018) Yildirim, Ender; Eryilmaz, Merve; Selbes, Yesim; Saglam, Necdet; Tamer, Ugur; Gjergjizi, Belma; Cogun, Ferah
Human luteinizing hormone (LH) is an important analyte for doping control analysis since it increases the athletic performance. However, traditional methods to detect LH have few disadvantages, such as long analysis duration, waste disposal problem and sample matrix effect. Addressing these problems, surface enhanced Raman spectroscopy based LH analysis using a passive microfluidic chip was developed and optimized. Antibody modified magnetic gold nanoparticles captured the LH and then, 4-aminothiophenol (4-ATP) labeled nanoparticles formed the sandwich immunoassay structure. The complex and the other reactions occurred in different chambers of the chip. The SERS signals of 4-ATP were recorded from the chamber and the system was shown to detect 0.036 IU L-1 in serum samples. The performance of the immunoassay was compared to all other methods and the proposed assay was the fastest analysis of LH without any problems associated with the sensitivity. The shorter analysis time was recorded because the chip enables the control of all reactions in one place and there was no requirement of a specialized laboratory. (c) 2018 Elsevier B.V. All rights reserved.
Citation - WoS: 7
Citation - Scopus: 7
Thermo-Fluid Multi-Physics Modeling and Experimental Verification of Volumetric Workpiece Material Removal by a Discharge Pulse in Electric Discharge Machining Process
(Iop Publishing Ltd, 2020) Cogun, Can; Uslan, Ibrahim; Erbas, Murat; Erdem, Oguz
The volume of material removed from the workpiece by a pulse (V-v) in the electric discharge machining was quantitatively determined using a multi-physics simulation model in ANSYS CFX software. Electrical heating is used in the model to simulate the plasma channel formation by defining the boundary and time-controlled current density initial conditions. Time-dependent physical properties at plasma temperature were used to reflect the actual processing environment. The heat was transferred from the plasma channel to the workpiece by electrical heating from the electrode, and V(v)was calculated by means of the amount of heat transfer. The calculated V(v)values for AISI4140, Ti6Al4V and Inconel 718 workpieces were lower than the experimental results and the difference was observed to change between 38.3% and 46.9%.

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