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.
Citation - WoS: 20
Citation - Scopus: 22
A Comparison of Iterative Fourier Transform Algorithms for Image Quality Estimation
(Optical Soc Japan, 2018) Alsaka, Dina Yaqoob; Arpali, Caglar; 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.
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: 14
Citation - Scopus: 13
Electrochemical Small Diameter Deep Hole Drilling of Powder Metal Steel
(Univ Zagreb Fac Mechanical Engineering & Naval Architecture, 2020) Cogun, Can; Ozerkan, Haci Bekir
In this study, a new hybrid electrochemical drilling (ECD) method is proposed. The method makes use of a tubular tool capable of rotating and an electrolyte flushing through the inner hole at the same time. The designed and manufactured small size ECD machine's most important features are the regulation of the tool feed rate via current feedback control and the use of a rotating tubular tool with internal electrolyte flushing. The powder metal (PM) FLN2 4405 steel was drilled by using a brass tubular tool with various combinations of machining parameters such as machining voltage, electrolyte concentration and flushing pressure, and tool rotation speed. The machining performance outputs, namely, material removal rate (MRR), average radial overcut (RADOC), conicity (CO) and hole geometries were calculated and compared in different machining conditions. The results have shown that the aforementioned variables had a direct impact on the machining performance outputs in ECD. In all experiments, MRR increased with an in increase in machining voltage, tool rotational speed, electrolyte concentration and flushing pressure. RADOC values decreased with the rotational speed of the tool. The present study shows that deep holes with precise geometries and dimensions can be drilled successfully by employing the proposed hybrid ECD method. The method is economical and environmentally friendly since it requires low machining current values (0.1 to 0.7A) and a small amount of non-hazardous halide salt solutions instead of acidic solutions throughout the drilling process.

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