Mühendislik Fakültesi / Faculty of Engineering

Permanent URI for this collectionhttps://hdl.handle.net/11727/1401

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    Exploring The Viability Of Alternative Cooling-Lubrication Strategies İn Machining Processes: A Comprehensive Review On The Performance And Sustainability Assessment
    (Başkent Üniversitesi Mühendislik Fakültesi, 2024-02-19) Roy, Soumikh; Das, Anshuman; Kumar, Ramanuj; Das, Sudhansu Ranjan; Rafighi, Mohammad; Sharma, Priyaranjan
    This paper explores the challenges of machining difficult-to-cut metals using tools like coated carbide, ceramics, and CBN under dry conditions, addressing issues such as heat generation, tool wear and friction, chip evacuation, surface integrity, vibration, and chatter. Though cutting fluids have historically improved machinability, environmental concerns, such as toxicity and non-biodegradability, are significant. Researchers aim to enhance the economic and ecological aspects of machining by reducing cutting fluid usage. This paper provides an overview of the performance assessment and sustainability evaluation of various cooling and lubrication methods during the machining of hard-to-machine as well as difficult-to-cut metals. Additionally, the literature review highlights various environmentally friendly cooling strategies, such as minimum quantity lubrication (MQL) and cryogenic arrangements. According to the results of this review, the utilization of various cooling and lubrication technologies has the potential to enhance both sustainability and machinability properties while prolonging the lifespan of cutting tools. The findings also show that there is a lot of room for improvement in terms of optimizing and making these cooling-lubrication solutions more practical and effective.
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    ParsyBot: Chatbot for Baskent University Related FAQs
    (18TH IEEE INTERNATIONAL CONFERENCE ON SEMANTIC COMPUTING, ICSC 2024, 2024-05-17) Karkiner, Zeynep; Yaman, Begum; Zengin, Begum; Cavli, Feride Nursena; Sert, Mustafa
    Reading regulations and instructions may take lots of time and sometimes it results in disappointments. To avoid this issue, people are prone to use sources that provide fast and accurate answers while accessing the information. Chatbots, are one of the most popular trend topics nowadays, and may adapted into various fields e.g., healthcare, finance, and education. This paper proposes the development of ParsyBot which is a Turkish chatbot designed to inform users about the regulations, admissions, departments, scholarships, and social clubs of Baskent University. Furthermore, users may ask via voice in Turkish this feature is not common among the other chatbots. ParsyBot uses a pre-trained BERT model which is specifically trained with regulations and instructions of Baskent University. Parsybot runs on web and mobile platforms to make it available for everyone. Our experiments on the utilized dataset, ParsyBot, reached 0.81 in METEOR, and 0.24 in ROGUE-1, which are promising compared to the ChatGPT 3.5.
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    Implementation of Smooth Transitions for Grid Connected PV System between the Operating Modes
    (18TH INTERNATIONAL CONFERENCE ON COMPATIBILITY, POWER ELECTRONICS AND POWER ENGINEERING, CPE-POWERENG 2024, 2024-10-02) Onar, Burak; Fesli, Ugur; Demirbas, Sevki
    The grid-connected PV microgrid needs coordination among the components, compromising the whole system to supply the power required by the loads. Well-designed energy management and control structures should be ensured to operate grid-connected PV microgrids with smooth and uninterruptible power. Much of the power system instability arises from transitions between grid-connected mode and island mode. This study introduces a control method to ensure a smooth transition between operating modes for PV microgrids operating in both grid-connected and island modes. The proposed control method has been verified with simulation performed with Matlab & Simulink simulation programs.
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    Sarcasm Detection in News Headlines with Deep Learning
    (32ND IEEE SIGNAL PROCESSING AND COMMUNICATIONS APPLICATIONS CONFERENCE, SIU 2024, 2024-12-05) Karkiner, Zeynep; Sert, Mustafa
    Sarcasm detection is one of the recent topics studied in the field of natural language processing. Although sarcasm detection is generally carried out through social media comments in the literature, it can also be applied to news headlines that are expected to be completely objective and reflect reality. In this study, sarcasm detection was carried out using various deep learning models in a dataset containing sarcastic and non-sarcastic news headlines. The accuracy of classification results of BERT, RNN, LSTM, and GRU models and their training time performance were compared. While the BERT model reached the highest accuracy (0.88), RNN was the most successful model in terms of training time performance.
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    Lyapunov-based Controller Design for Precise Monitoring, Speed Control and Trajectory Planning in Autonomous Tractors with Trailers
    (32ND IEEE SIGNAL PROCESSING AND COMMUNICATIONS APPLICATIONS CONFERENCE, 2024-12-05) Aydin, Gulsah Demirhan; Dogan, Deren; Turken, Yusuf Tugberk
    Nowadays, modern technology-based agriculture operations are replacing traditional farming practices. Smart agricultural systems have gained popularity as a result of the demand for more productive and environmentally friendly farming methods. Consequently, the agricultural sector continues to be one of the driving forces behind automation, viewing technological advancements as a means of increasing productivity while lowering costs. Automation in agriculture ranges from tractors built with apparatus that can carry out complicated tasks on their own to cultivation surveillance. This study aims to optimize the speed of an autonomous tractor through a dynamic code based on Lyapunov control method as an innovative approach in smart agriculture. Beyond speed optimization, the research also addresses practical challenges encountered in real-world scenarios, including obstacles such as living entities. By evaluating the potential of Lyapunov control methodology in the effective management of agricultural machinery, this work offers an innovative perspective on smart agricultural technologies.
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    A Hybrid Monte Carlo Simulation Risk Model for Oil Exploration Projects
    (MARINE POLLUTION BULLETIN, 2023) Balas, Egemen Ander
    A new 3-D Hybrid Monte Carlo Simulation (MCS) Risk Model is proposed in this study. The wind, wave, current, climate change, and tsunami sub-models of the Three-Dimensional Hydrodynamic Transport and Water Quality Model HYDROTAM-3D are interrelated with MCS, to obtain probability distributions for the simulation of environmental conditions. This is the only model that can incorporate the tsunami, storm, and sea level rise risks in oil exploration projects. The spill risk index (SRI) of 50 blue barrels spilled due to a blowout from the rig/port during fuel supply was circa 1 ton/ship as Tier I with an average annual occurrence probability of 1.0 x 10-6. The discharge of 4000 bbls for 6 h was modeled, resulting in the SRI of 546 metric tons from the riser blowout with SRI = 0.2 per meter, indicating a Tier II risk. The mean arrival time of this spill was found by MCS as 145 min.
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    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, Kaizhou
    In 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.
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    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.
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    Mechanical and Morphological Investigation of Laminated Composite Polymers Depending on Increasing Vibration Cycle
    (2023) Kemiklioglu, Ugur; 0000-0002-5597-1256
    Composite 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.
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    Toward Camouflage Colors by Electrochemical Copolymerization
    (2023) Ergun, Emine Gul Cansu; Carbas, Buket Bezgin
    In 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.image