Mühendislik Fakültesi / Faculty of Engineering
Permanent URI for this collectionhttps://hdl.handle.net/11727/1401
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Item Intelligent Optimization Under the Makespan Constraint: Rapid Evaluation Mechanisms Based on the Critical Machine for the Distributed Flowshop Group Scheduling Problem(2023) Wang, Yuhang; Han, Yuyan; Wang, Yuting; Tasgetiren, M. Fatih; Li, Junqing; Gao, KaizhouIn the flowshop scheduling literature, the insertion-based neighborhood search method is often considered to obtain high-quality solutions. It will lead to expending extensive computational effort when evaluating the objective function. Rapid evaluation methods based on Taillard's acceleration can reduce the time complexity of function evaluation. However, existing rapid evaluation methods cannot be applied directly to the distributed flowshop group scheduling problem (DFGSP), especially to minimize the total tardiness time objective. Thus, we first proposed two theorems and their proofs based on the critical machine. Then, two rapid evaluation methods based on these theorems are proposed to accelerate the evaluation of the objective. Considering the multiple coupled sub-problems in the DFGSP, we proposed a cooperative iterated greedy algorithm (CIG) combining two rapid evaluation methods, in which intergroup and intra-group neighborhood search strategies are proposed to enhance the search depth and breadth. Comprehensive statistical experiments show that computational effort is extensively decreased in the calculation of total tardiness time, and the CIG algorithm significantly outperforms the eight compared algorithms.& COPY; 2023 Elsevier B.V. All rights reserved.Item Diver Detection and Tracking with Different Beamforming Algorithms(2023) Sevimli, Rasim A.Diver Detection Sonars (DDS) aim to detect the diver and tracking at the specific distance. At the side of signal processing case, there are bunch of beamforming algorithms to localize the target or diver in our case in the literature. In this paper, some beamforming algorithms are combined and compared via PSNR, time each other. Some algorithms show that the effect of sidelobes and reverberation are clearly decreased. Moreover, detection and tracking algorithms are applied to artificial sonar data created with a specific scenario for this purpose.Item Mechanical and Morphological Investigation of Laminated Composite Polymers Depending on Increasing Vibration Cycle(2023) Kemiklioglu, Ugur; 0000-0002-5597-1256Composite polymers are widely used in vibrating environments such as the aerospace, automotive, marine, and sports industries. Accordingly, composite materials are exposed to vibration at various periods. In this study, the effect of the vibration cycle on the mechanical properties of composite plates was investigated. The plates were vibrated at different revolutions. The tensile strength of these plates after vibration was examined, and these effects were compared with each other. As the vibration cycle increased, it was observed that tensile damage gradually occurred at different angles, and scanning electron microscopy (SEM) analysis revealed that the fibers were damaged at different angles. Accordingly, it was observed that the increased vibration cycle caused an angular fracture in the composite plates and decreased the tensile strength from 9.7 to 7.9 kN by nearly 23% as well as the elongation from 3.4 to 2.76 mm.Item Toward Camouflage Colors by Electrochemical Copolymerization(2023) Ergun, Emine Gul Cansu; Carbas, Buket BezginIn this paper, a new electrochromic copolymer containing 6,9-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-1,2,3,4-tetrahydrophenazine (EBE) and 4-(9-benzyl-9H-carbazol-3-yl)-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole (CBT) in the main chain was reported. The homopolymers, (Poly(EBE) and Poly(CBT)), were also prepared via electrochemical polymerization and their electrochemical, spectroelectrochemical and electrochromic properties were analyzed in order to compare their properties with those of copolymer (Poly(EBE-co-CBT)). The copolymer exhibited good switching property for military camouflage necessities with color change from hues of brown to green. Furthermore, it has been tried to analyze the effects of combination of two donor-acceptor-donor (DAD) type monomers with different symmetries on the copolymer properties. A viable strategy for electrochromic adaptive camouflage was presented. New electrochromic copolymer film containing 6,9-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-1,2,3,4-tetrahydrophenazine and 4-(9-benzyl-9H-carbazol-3-yl)-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole in the main chain was synthesized using electrochemical polymerization technique. The resulting copolymer film matched the military camouflage necessities with having color changes from hues of brown to green. Moreover, an "asymmetric and symmetric donor-acceptor-donor type monomeric combination" in an electrodeposited copolymer film was first time presented.imageItem Electrochromic Insight on Electro-Deposited Copolymers of Push-Pull Conjugated Systems with 3,4-Ethylenedioxythiophene (EDOT) and Other Conjugated Units(2023) Ergun, Emine Gul Cansu; Hacioglu, Serife OzdemirThird generation conducting polymers (CP) are push-pull type conjugated systems, which include both electron pushing and pulling units in their chemical structure. Push-pull design enables coarse and fine tuning in the electro-optical properties of the resulting CP such as lowering the band gap and enhancing electrochromic properties. Push-pull CPs have been widely used for various applications such as electrochromic devices, displays, light emitting diodes, organic solar cells, field effect transistors, electrochemical and optical sensors etc. This review aims to collect electrochemically synthesized CPs of push-pull systems in the literature, up to 2023. Most of the studies include 3,4-ethylenedioxythiophene (EDOT) as co-monomers, but there are also other studies such as obtaining push-pull type CPs by copolymerization, and copolymerization of push-pull systems with other units. Each case is discussed in separate sections. In the scope of this review, only electrochemical copolymerization studies are selected, and the effect of monomer feed ratio and the polymerization conditions on the electrochromic properties of the resulting copolymers are discussed and summarized in tables. This collection can serve as a guide for upcoming copolymerization studies, by giving an insight into optical and electrochromic properties of various copolymers of push-pull systems so far. A comprehensive literature survey about electrochemical copolymerization of push-pull type conjugated systems with 3,4-ethylenedioxythiophene (EDOT) and other conjugated units. Effect of monomer feed ratio and polymerization conditions on the electrochromic properties of resulting copolymers were discussed.imageItem RadGT: Graph and Transformer-Based Automotive Radar Point Cloud Segmentation(2023) Sevimli, Rasim A.; Ucuncu, Murat; Koc, Aykut; 0000-0002-2113-1398; KDO-6837-2024The need for visual perception systems providing situational awareness to autonomous vehicles has grown significantly. While traditional deep neural networks are effective for solving 2-D Euclidean problems, point cloud analysis, particularly for radar data, contains unique challenges because of the irregular geometry of point clouds. This letter proposes a novel transformer-based architecture for radar point clouds adapted to the graph signal processing (GSP) framework, designed to handle non-Euclidean and irregular signal structures. We provide experimental results by using well-established benchmarks on the nuScenes and RadarScenes datasets to validate our proposed method.Item Multimodal Video Captioning Using Object-Auditory Information Fusion with Transformers(2023) Selbes, Berkay; Sert, MustafaVideo captioning aims to generate natural language sentences of an input video. Generating coherent natural language sentences is a challenging task due to the complex nature of video content such as object and scene understanding, extraction of object- and event-specific auditory information, and acquisition of relationships among objects. In this study, we address the problem of efficient modeling of object interactions in scenes, as they include crucial information regarding the events in the visual scene. To this end, we propose to use object features along with auditory information to better model the audio-visual scene appearing within the video. Specifically, we extract Faster R-CNN as the object features and VGGish as the auditory features and design a transformer encoder-decoder architecture in the multimodal setup. Experiments on MSR-VTT show encouraging results and object features better model the object interactions along with the auditory information in comparison to the ResNet features.Item Six Sigma Project Prioritization and Selection Using AHP-CODAS Integration: A Case Study in Healthcare Industry(2023) Can, Gulin Feryal; Toktas, Pelin; Pakdil, Fatma; https://orcid.org/0000-0001-6622-4646; D-7271-2018Given the complex nature of Six Sigma project (SSP) prioritization and selection processes, multicriteria decision-making (MCDM) methods may help organizations identify the most effective projects. Considering potential limitations of subjective methods and advantages of MCDM methods, this article proposes a model that integrates analytical hierarchy process (AHP) and combinative distance-based assessment (CODAS) in SSP prioritization and selection process. In the proposed approach, AHP is employed to assign criteria weights, and CODAS is performed to determine priorities of SSPs. CODAS was advanced in term of its threshold function. Differences between Euclidean distances of two alternatives were compared, based on the standard deviation of Euclidean distances of all alternatives to overcome the subjectivity. This is the first study that combines AHP and CODAS methods for SSP selection, and CODAS is used with objective threshold value computation, and developed for the healthcare industry. In this article, ten SSPs were evaluated for four key criteria groups as financial, operational, patient centric, and organizational main criteria groups. In total, 18 subcriteria were considered under these four main criteria groups. This article provides a support for executives who make implementation plans for the potential SSPs.Item Goodness-of-fit and Randomness Tests for the Sun's Emissions True Random Number Generator(2014) Tanyer, Suleyman Gokhun; Atalay, Kumru Didem; Inam, Sitki Cagdas; 0000-0003-0820-9186; I-5023-2013; JHU-3888-2023Random number generators ( RNGs) are one of the key tools necessary for statistical analysis and optimization methods such as Monte Carlo, particle swarm optimization ( PSO) and the genetic algorithm. Various pseudo and true RNGs are available today, and they provide sufficient randomness. Unfortunately, they generate data that do not always represent the required distribution accurately, especially when the data length is small. This could possibly threaten the 'repeatability' of an academic study. A novel true RNG ( TRNG) using the method of uniform sampling ( MUS) is recently proposed. In this work, the Sun's RF emissions MUS-TRNG is comparatively tested with well known pseudo and true RNGs. It is observed that both randomness and very high goodness-of-fit qualities are possible.Item True Random Number Generation of Very High Goodness-of-fit and Randomness Qualities(2014) Tanyer, Suleyman Gokhun; I-5023-2013The statistical nature of numerous problems in mathematics, physics and engineering have led to the development of methods for generating random data for a given distribution. Ancient methods include; dice, coin flipping and shuffling of cards. Today, various pseudo, quasi and true random generators ( RNGs) are being proposed for their improved properties. In this work, test metrics for goodness-of-fit and randomness are reviewed. The method of uniform sampling ( MUS) is modified for improving the randomness without harming the goodness-of-fit qualities. The test results illustrate that very high goodness-of-fit can be obtained even when the number of observed samples is as small as 10.