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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/3
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Publication Metadata only Large language model-based chatbots in higher education(Wiley, 2024) Eryilmaz, Merve; Yetisen, Ail K.; Ozcan, Aydogan; Department of Mechanical Engineering; Yığcı, Defne; Taşoğlu, Savaş; Department of Mechanical Engineering; School of Medicine; College of EngineeringLarge language models (LLMs) are artificial intelligence (AI) platforms capable of analyzing and mimicking natural language processing. Leveraging deep learning, LLM capabilities have been advanced significantly, giving rise to generative chatbots such as Generative Pre-trained Transformer (GPT). GPT-1 was initially released by OpenAI in 2018. ChatGPT's release in 2022 marked a global record of speed in technology uptake, attracting more than 100 million users in two months. Consequently, the utility of LLMs in fields including engineering, healthcare, and education has been explored. The potential of LLM-based chatbots in higher education has sparked significant interest and ignited debates. LLMs can offer personalized learning experiences and advance asynchronized learning, potentially revolutionizing higher education, but can also undermine academic integrity. Although concerns regarding AI-generated output accuracy, the spread of misinformation, propagation of biases, and other legal and ethical issues have not been fully addressed yet, several strategies have been implemented to mitigate these limitations. Here, the development of LLMs, properties of LLM-based chatbots, and potential applications of LLM-based chatbots in higher education are discussed. Current challenges and concerns associated with AI-based learning platforms are outlined. The potentials of LLM-based chatbot use in the context of learning experiences in higher education settings are explored. The use of large language models (LLMs) in higher education can facilitate personalized learning experiences, advance asynchronized learning, and support instructors, students, and researchers across diverse fields. The development of regulations and guidelines that address ethical and legal issues is essential to ensure safe and responsible adaptation of LLM-based tools in real-world educational settings.Publication Metadata only Experimental estimation of gap thickness and electrostatic forces between contacting surfaces under electroadhesion(Wiley, 2024) Martinsen, Orjan Grottem; Pettersen, Fred-Johan; Colgate, James Edward; Department of Mechanical Engineering; Aliabbasi, Easa; Başdoğan, Çağatay; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; College of EngineeringElectroadhesion (EA) is a promising technology with potential applications in robotics, automation, space missions, textiles, tactile displays, and some other fields where efficient and versatile adhesion is required. However, a comprehensive understanding of the physics behind it is lacking due to the limited development of theoretical models and insufficient experimental data to validate them. This article proposes a new and systematic approach based on electrical impedance measurements to infer the electrostatic forces between two dielectric materials under EA. The proposed approach is applied to tactile displays, where skin and voltage-induced touchscreen impedances are measured and subtracted from the total impedance to obtain the remaining impedance to estimate the electrostatic forces between the finger and the touchscreen. This approach also marks the first instance of experimental estimation of the average air gap thickness between a human finger and a voltage-induced capacitive touchscreen. Moreover, the effect of electrode polarization impedance on EA is investigated. Precise measurements of electrical impedances confirm that electrode polarization impedance exists in parallel with the impedance of the air gap, particularly at low frequencies, giving rise to the commonly observed charge leakage phenomenon in EA. A novel and systematic approach is introduced, leveraging electrical impedance measurements to infer electrostatic forces between two dielectric materials under electroadhesion (EA). This innovative approach holds promise for diverse applications spanning robotics, automation, space missions, textiles, and tactile displays. Furthermore, this study sheds light on the physics of EA, offering valuable insights with implications for the design of electroadhesive devices.Publication Metadata only A front tracking method for direct numerical simulation of evaporation process in a multiphase system(Academic Press Inc Elsevier Science, 2017) N/A; N/A; Department of Mechanical Engineering; Irfan, Muhammad; Muradoğlu, Metin; PhD Student; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 46561A front-tracking method is developed for the direct numerical simulation of evaporation process in a liquid-gas multiphase system. One-field formulation is used to solve the flow, energy and species equations in the framework of the front tracking method, with suitable jump conditions at the interface. Both phases are assumed to be incompressible; however, the divergence-free velocity field condition is modified to account for the phase-change/mass-transfer at the interface. Both temperature and species gradient driven evaporation/phase-change processes are simulated. For the species gradient driven phase change process, the Clausius-Clapeyron equilibrium relation is used to find the vapor mass fraction and subsequently the evaporation mass flux at the interface. A number of benchmark cases are first studied to validate the implementation. The numerical results are found to be in excellent agreement with the analytical solutions for all the studied cases. The methods are then applied to study the evaporation of a static as well as a single and two droplets systems falling in the gravitational field. The methods are demonstrated to be grid convergent and the mass is globally conserved during the phase change process for both the static and moving droplet cases.Publication Metadata only A front-tracking method for computation of interfacial flows with soluble surfactants(Academic Press Inc Elsevier Science, 2008) Tryggvason, Gretar; Department of Mechanical Engineering; Muradoğlu, Metin; Faculty Member; Department of Mechanical Engineering; College of Engineering; 46561A finite-difference/front-tracking method is developed for computations of interfacial flows with soluble surfactants. The method is designed to solve the evolution equations of the interfacial and bulk surfactant concentrations together with the incompressible Navier-Stokes equations using a non-linear equation of state that relates interfacial surface tension to surfactant concentration at the interface. The method is validated for simple test cases and the computational results are found to be in a good agreement with the analytical solutions. The method is then applied to study the cleavage of drop by surfactant-a problem proposed as a model for cytokinesis [H.P. Greenspan, On the dynamics of cell cleavage, J. Theor. Biol. 65(l) (1977) 79; H.P. Greenspan, On fluid-mechanical simulations of cell division and movement, J. Theor. Biol., 70(l) (1978) 125]. Finally the method is used to model the effects of soluble surfactants on the motion of buoyancy-driven bubbles in a circular tube and the results are found to be in a good agreement with available experimental data.Publication Metadata only Characterization of frequency-dependent material properties of human liver and its pathologies using an impact hammer(Elsevier, 2011) Dogusoy, Gulen; Tokat, Yaman; N/A; N/A; Department of Mechanical Engineering; Özcan, Mustafa Umut; Öcal, Sina; Başdoğan, Çağatay; Master Student; Master Student; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 125489The current methods for characterization of frequency-dependent material properties of human liver are very limited. In fact, there is almost no data available in the literature showing the variation in dynamic elastic modulus of healthy or diseased human liver as a function of excitation frequency. We show that frequency-dependent dynamic material properties of a whole human liver can be easily and efficiently characterized by an impact hammer. The procedure only involves a light impact force applied to the tested liver by a hand-held hammer. The results of our experiments conducted with 15 human livers harvested from the patients having some form of liver disease show that the proposed approach can successfully differentiate the level of fibrosis in human liver. We found that the storage moduli of the livers having no fibrosis (F0) and that of the cirrhotic livers (F4) varied from 10 to 20 kPa and 20 to 50 kPa for the frequency range of 0-80 Hz, respectively.Publication Metadata only A new model and direct slicer for lattice structures(Springer, 2021) N/A; N/A; Department of Mechanical Engineering; Mustafa, Syed Shahid; Lazoğlu, İsmail; PhD Student; Faculty Member; Department of Mechanical Engineering; Manufacturing and Automation Research Center (MARC); Graduate School of Sciences and Engineering; College of Engineering; N/A; 179391This paper presents a model for generating strut-based lattice structures using topology optimization and their efficient direct slicing. These structures exhibit better physical properties and can represent the partial densities at the macro-scale level, which often appear in designs based on topology optimization. The fabrication of such large member structures with intricate geometries is possible by the additive manufacturing technologies which offer design freedom to produce the optimized parts for engineering applications. However, these structures generate millions of planer manifolds describing the strut members and result in large data files, thus making conventional procedures in additive manufacturing highly ineffective. Therefore, the design process for such structures requires efficient data manipulation and storage of the lattice topology. In the current work, a mathematical model for the strut primitive which connects two nodes in a cell is developed. Based on the proposed strut model, a structural optimization formulation is presented for lattice structures design under volume fraction constraint. A matrix-oriented compact data structure to express the lattice topology and the direct slicing algorithm which makes queries on the proposed compact data structure is presented as part of this work. The slicing kernel has been tailored for parallel implementation to handle engineering-scale applications which often consist of structures over a million struts. The article is organized into the "Introduction" section explaining the requirement and the novelty of this work. Following which, the automated design framework based on topology optimization procedure for lattice structures is given. The mathematical derivations and data structure of the strut-based lattice will be explained and the operations on model data for the direct slicing procedure are elaborated. Numerical experiments verifying the proposed method will be presented toward the end.Publication Metadata only Adaptive human force scaling via admittance control for physical human-robot interaction(IEEE Computer Soc, 2021) Aydın, Yusuf; N/A; Department of Mechanical Engineering; Al Qaysi, Yahya Mohey Hamad; Başdoğan, Çağatay; PhD Student; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 125489The goal of this article is to design an admittance controller for a robot to adaptively change its contribution to a collaborative manipulation task executed with a human partner to improve the task performance. This has been achieved by adaptive scaling of human force based on her/his movement intention while paying attention to the requirements of different task phases. In our approach, movement intentions of human are estimated from measured human force and velocity of manipulated object, and converted to a quantitative value using a fuzzy logic scheme. This value is then utilized as a variable gain in an admittance controller to adaptively adjust the contribution of robot to the task without changing the admittance time constant. We demonstrate the benefits of the proposed approach by a pHRI experiment utilizing Fitts' reaching movement task. The results of the experiment show that there is a) an optimum admittance time constant maximizing the human force amplification and b) a desirable admittance gain profile which leads to a more effective co-manipulation in terms of overall task performance.Publication Metadata only A monolithic opto-coupler based sensor for contact force detection in artificial hand(Ieee, 2016) N/A; N/A; Department of Mechanical Engineering; Shams, Sarmad; Lazoğlu, İsmail; PhD Student; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 179391This paper presents a monolithic opto-coupler based force sensor design to detect the contact forces of the fingertip of the artificial hand during grasp process. Effective and precise measurement of the contact force is always a challenge for the humid and temperature varying environment. In this paper, we propose a novel design of force sensor with optical technique. The optical technique is preferred over other techniques because of its simpler electronics and less immunity to temperature variation under humid environment. Simulation results conducted using Finite Element Method (FEM) analysis confirmed the deflection is linear for the forces from 0 to +/- 100 N. The maximum stress found at 100 N is 252.39 MPa. Also, modal analysis is performed to ensure the sensor is durable and operative while handling different vibrating objects. Calibration experiment of the sensor is performed using multipoint calibration process and curve fitting technique.Publication Metadata only Probing human-soundscape interaction using observational user experience methods(Assoc Computing Machinery, 2016) N/A; Department of Mechanical Engineering; Department of Media and Visual Arts; Yücetürk, Selman; Obaid, Mohammad; Yantaç, Asım Evren; Master Student; Undergraduate Student; Faculty Member; Department of Mechanical Engineering; Department of Media and Visual Arts; Graduate School of Social Sciences and Humanities; College of Engineering; College of Social Sciences and Humanities; N/A; N/A; 52621Sound, whose perception depends on spatial, temporal and cognitive factors, is an intangible issue within interaction design. It is not very easy for interaction designers to explore, understand, or ideate on this intangible and complex phenomenon as they mostly rely on visual language, sketches, or physical prototypes. In this paper, we present initial insights to the design of an interactive mediated sound reality system, which refines the users' interaction with a soundscape. The main contribution of this study is the insights gathered through the use of three observational user experience (UX) methods: (1) note-taking in soundwalks; (2) soundscape visualization; (3) auditory journey maps to overcome the above-mentioned difficulty in rationalizing the intangibility of human-soundscape interaction with focusing, recording and reflecting spatial, temporal and interactive aspects of soundscape.Publication Metadata only Sensation: Measuring the effects of a human-to-human social touch based controller on the player experience(Assoc Computing Machinery, 2016) N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Department of Mechanical Engineering; Department of Computer Engineering; Department of Psychology; N/A; Department of Psychology; Department of Media and Visual Arts; Canat, Mert; Tezcan, Mustafa Ozan; Yurdakul, Celalettin; Tiza, Eran; Sefercik, Buğra Can; Bostan, İdil; Buruk, Oğuz Turan; Göksun, Tilbe; Özcan, Oğuzhan; Undergraduate Student; Undergraduate Student; Undergraduate Student; Undergraduate Student; Undergraduate Student; Undergraduate Student; PhD Student; Faculty Member; Faculty Member; Department of Electrical and Electronics Engineering; Department of Mechanical Engineering; Department of Computer Engineering; Department of Psychology; Department of Media and Visual Arts; KU Arçelik Research Center for Creative Industries (KUAR) / KU Arçelik Yaratıcı Endüstriler Uygulama ve Araştırma Merkezi (KUAR); College of Engineering; College of Engineering; College of Engineering; College of Engineering; College of Engineering; College of Social Sciences and Humanities; Graduate School of Social Sciences and Humanities; College of Social Sciences and Humanities; College of Social Sciences and Humanities; N/A; N/A; N/A; N/A; N/A; N/A; N/A; 47278; 12532We observe an increasing interest on usage of full-body interaction in games. However, human-to-human social touch interaction has not been implemented as a sophisticated gaming apparatus. To address this, we designed the Sensation, a device for detecting touch patterns between players, and introduce the game, Shape Destroy, which is a collaborative game designed to be played with social touch. To understand if usage of social touch has a meaningful contribution to the overall player experience in collaborative games we conducted a user study with 30 participants. Participants played the same game using i) the Sensation and ii) a gamepad, and completed a set of questionnaires aimed at measuring the immersion levels. As a result, the collected data and our observations indicated an increase in general, shared, ludic and affective involvement with significant differences. Thus, human-to-human touch can be considered a promising control method for collaborative physical games.