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Conference Object An Investigation About Process Matchmaking Performances of Unstructured and Decentralized Digital Environments(Ieee, 2007) Cakir, Bugra; Kilic, HurevrenEfficient matchmaking is an important problem in unstructured and decentralized digital environments. We report the results of simulations of these environments and provide measurements of match performance focusing on unstructured and decentralized environments. In the study, different environment models including P2P (Hypergrid, Gnutella with/without ultrapeer); small-world (Watts-Strogatz); heavy-tailed and random versions of Autonomous System Waxman model showing power-law distribution property; random and 2D-Grid are considered. The flooding mechanism enabling process encounters for match purposes is uninformed Breadth-First-Search. Simulations show that the matchmaking performance of random environment outperforms the others for almost all different problems and time-to-live settings. On the other hand, the total cost of small world environment model is the highest for almost all setups.Conference Object Simulation Based Surgical Education Programs and Hand Performance;(Institute of Electrical and Electronics Engineers Inc., 2017) Eyuboglu,B.G.; Topalli,D.; Cagiltay,N.E.; Tonbul,G.The performance of the left- and right-hands of a person may be different from each other. In general, people use one hand with a superior performance compared to the other hand where that hand is preferred for performing daily activities. It is critical to understand their preference for right or left hand use, especially in cases where the skills should be improved to use both hands precisely in activities required special abilities such as endoscopic surgical operations. A better understanding of these cases will improve the quality of existing surgical education programs, and make a major contribution specifically in designing, improving and managing of simulation-based instructional technologies. In this study, the right- and left-hand preferences (handedness) of people are analyzed from the literature and a simulation-based experimental study is conducted in order to examine the performance differences of the participants while using their right and left hands. The results of this study aimed to guide the curriculum designers and instructional system developers for better designing and developing simulation-based surgical education programs. © 2016 IEEE.Conference Object An Experimental Study for Simulation Based Assessment of Information System Design Performance(int Assoc Engineers-iaeng, 2007) Ayyildiz, Bulent; Akman, Ibrahim; Arifoglu, AliThis paper presents an experimental study for evaluating the decision support value of queueing network (QN) based simulation models for information system design performance. For illustration, queueing network simulation models have been extracted corressponding to three annotated design alternatives of a selected case study. The design alternatives are produced using logical requirements of the selected system. The performance of each alternative is then predicted using quantifiable parameters considering the dynamics of the system such as service time, waiting time and number of entities waiting in the system. In particular, results have shown that the first alternative performs better than the other two in terms of the selected parameters. In general, the case study revealed that QN-based simulation models are capable to distinguish the performance of design alternatives in terms of selected parameters and under given assumptions. This also means that the use of simulation may lead to better designed information systems.Article Citation - WoS: 8Citation - Scopus: 7The Underlying Reasons of the Navigation Control Effect on Performance in a Virtual Reality Endoscopic Surgery Training Simulator(Taylor & Francis inc, 2019) Cagiltay, Nergiz Ercil; Ozcelik, Erol; Berker, Mustafa; Dalveren, Gonca Gokce MenekseNavigation control skills of surgeons become very critical for surgical procedures. Strategies improving these skills are important for developing higher-quality surgical training programs. In this study, the underlying reasons of the navigation control effect on performance in a virtual reality-based navigation environment are evaluated. The participants' performance is measured in conditions: navigation control display and paper-map display. Performance measures were collected from 45 beginners and experienced residents. The results suggest that navigation display significantly improved performance of the participants. Also, navigation was more beneficial for beginners than experienced participants. The underlying reason of the better performance in the navigation condition was due to lower number of looks to the map, which causes attention shifts between information sources. Accordingly, specific training scenarios and user interfaces can be developed to improve the navigation skills of the beginners considering some strategies to lower their number of references to the information sources.Conference Object Simulations for Surgical Education: a Case Study for Endoneurosurgery(Iated-int Assoc Technology Education A& development, 2015) Berker, Mustafa; Cagiltay, Nergiz Ercil; Isikay, IlkayToday, introduction of the microscope and later the extensive use of the video camera have changed the way operations are performed which have replaced the direct vision by a video image. These types of surgical techniques are generally called as minimal invasive surgery (MIS). Laparoscopic surgery and endoscopic surgery fall in this category. These new technologies require some additional skills to be gained during the surgical education and training programs. Most of the traditional surgical training takes place in the operating theater under the supervision of an experienced surgeon which does not allow any try-and-error type of learning, and does not tolerate errors. Hence, alternative educational methods by providing try-and-error type of learning are a critical for medical education. This study presents a simulation environment developed specifically for the pituitary surgery operations. The simulation environment composed of two main parts: the skill-based education and the procedure-based education for the novice surgeons. This study shows the design and implementation of educational modules developed to provide try-and-error type of educational environments as a case study on pituitary surgery operations.Review Citation - WoS: 58Citation - Scopus: 64Operational Research: Methods and Applications(Taylor & Francis Ltd, 2024) Petropoulos, Fotios; Laporte, Gilbert; Aktas, Emel; Alumur, Sibel A.; Archetti, Claudia; Ayhan, Hayriye; Zhao, XuyingThroughout its history, Operational Research has evolved to include methods, models and algorithms that have been applied to a wide range of contexts. This encyclopedic article consists of two main sections: methods and applications. The first summarises the up-to-date knowledge and provides an overview of the state-of-the-art methods and key developments in the various subdomains of the field. The second offers a wide-ranging list of areas where Operational Research has been applied. The article is meant to be read in a nonlinear fashion and used as a point of reference by a diverse pool of readers: academics, researchers, students, and practitioners. The entries within the methods and applications sections are presented in alphabetical order. The authors dedicate this paper to the 2023 Turkey/Syria earthquake victims. We sincerely hope that advances in OR will play a role towards minimising the pain and suffering caused by this and future catastrophes.Conference Object Simulation Based Surgical Education Programs and Hand Performance(Ieee, 2015) Eyuboglu, Burak Gokberk; Topallı, Damla; Topalli, Damla; Çağıltay, Nergiz; Cagiltay, Nergiz Ercil; Tonbul, Gokcen; Topallı, Damla; Çağıltay, Nergiz; Information Systems Engineering; Software Engineering; Information Systems Engineering; Software EngineeringThe performance of the left-and right-hands of a person may be different from each other. In general, people use one hand with a superior performance compared to the other hand where that hand is preferred for performing daily activities. It is critical to understand their preference for right or left hand use, especially in cases where the skills should be improved to use both hands precisely in activities required special abilities such as endoscopic surgical operations. A better understanding of these cases will improve the quality of existing surgical education programs, and make a major contribution specifically in designing, improving and managing of simulation-based instructional technologies. In this study, the right-and left-hand preferences (handedness) of people are analyzed from the literature and a simulation-based experimental study is conducted in order to examine the performance differences of the participants while using their right and left hands. The results of this study aimed to guide the curriculum designers and instructional system developers for better designing and developing simulation-based surgical education programs.Article Citation - WoS: 18Citation - Scopus: 23Lead-Free Perovskite Homojunction-Based Htm-Free Perovskite Solar Cells: Theoretical and Experimental Viewpoints(Mdpi, 2023) Sajid, Sajid; Alzahmi, Salem; Salem, Imen Ben; Park, Jongee; Obaidat, Ihab M.Simplifying the design of lead-free perovskite solar cells (PSCs) has drawn a lot of interest due to their low manufacturing cost and relative non-toxic nature. Focus has been placed mostly on reducing the toxic lead element and eliminating the requirement for expensive hole transport materials (HTMs). However, in terms of power conversion efficiency (PCE), the PSCs using all charge transport materials surpass the environmentally beneficial HTM-free PSCs. The low PCEs of the lead-free HTM-free PSCs could be linked to poorer hole transport and extraction as well as lower light harvesting. In this context, a lead-free perovskite homojunction-based HTM-free PSC was investigated, and the performance was then assessed using a Solar Cell Capacitance Simulator (SCAPS). A two-step method was employed to fabricate lead-free perovskite homojunction-based HTM-free PSCs in order to validate the simulation results. The simulation results show that high hole mobility and a narrow band gap of cesium tin iodide (CsSnI3) boosted the hole collection and absorption spectrum, respectively. Additionally, the homojunction's built-in electric field, which was identified using SCAPS simulations, promoted the directed transport of the photo-induced charges, lowering carrier recombination losses. Homojunction-based HTM-free PSCs having a CsSnI3 layer with a thickness of 100 nm, defect density of 10(15) cm(-3), and interface defect density of 10(18) cm(-3) were found to be capable of delivering high PCEs under a working temperature of 300 K. When compared to formamidinium tin iodide (FASnI(3))-based devices, the open-circuit voltage (V-oc), short-circuit density (J(sc)), fill factor (FF), and PCE of FASnI(3)/CsSnI3 homojunction-based HTM-free PSCs were all improved from 0.66 to 0.78 V, 26.07 to 27.65 mA cm(-2), 76.37 to 79.74%, and 14.62 to 19.03%, respectively. In comparison to a FASnI(3)-based device (PCE = 8.94%), an experimentally fabricated device using homojunction of FASnI(3)/CsSnI3 performs better with V-oc of 0.84 V, J(sc) of 22.06 mA cm(-2), FF of 63.50%, and PCE of 11.77%. Moreover, FASnI(3)/CsSnI3-based PSC is more stable over time than its FASnI(3)-based counterpart, preserving 89% of its initial PCE. These findings provide promising guidelines for developing highly efficient and environmentally friendly HTM-free PSCs based on perovskite homojunction.Article Citation - WoS: 22Citation - Scopus: 26Insights From Pupil Size To Mental Workload of Surgical Residents: Feasibility of an Educational Computer-Based Surgical Simulation Environment (ece) Considering the Hand Condition(Sage Publications inc, 2018) Dalveren, Gonca Gokce Menekse; Cagiltay, Nergiz Ercil; Ozcelik, Erol; Maras, HakanThe advantage of simulation environments is that they present various insights into real situations, where experimental research opportunities are very limited-for example, in endoscopic surgery. These operations require simultaneous use of both hands. For this reason, surgical residents need to develop several motor skills, such as eye-hand coordination and left-right hand coordination. While performing these tasks, the hand condition (dominant, nondominant, both hands) creates different degrees of mental workload, which can be assessed through mental physiological measures-namely, pupil size. Studies show that pupil size grows in direct proportion to mental workload. However, in the literature, there are very limited studies exploring this workload through the pupil sizes of the surgical residents under different hand conditions. Therefore, in this study, we present a computer-based simulation of a surgical task using eye-tracking technology to better understand the influence of the hand condition on the performance of skill-based surgical tasks in a computer-based simulated environment. The results show that under the both-hand condition, the pupil size of the surgical residents is larger than the one under the dominant and nondominant hand conditions. This indicates that when the computer-simulated surgical task is performed with both hands, it is considered more difficult than in the dominant and nondominant hand conditions. In conclusion, this study shows that pupil size measurements are sufficiently feasible to estimate the mental workload of the participants while performing surgical tasks. The results of this study can be used as a guide by instructional system designers of skill-based training programs.Review Citation - WoS: 9Citation - Scopus: 14Simulation of Quenching: a Review(Amer Soc Testing Materials, 2012) Gur, C. Hakan; Simsir, CanerQuenching is an important part of the production chain of steel components. The final properties of the product are largely determined during this stage, and this renders quenching as one of the most critical stages of production, requiring design and optimization specific to the product. The simulation of quenching requires the solution of a multi-scale/multi-physics problem with complex boundary conditions because of the simultaneously occurring heat transfer, phase transformation, and mechanical interactions. The aim of this paper is to provide an updated review of research studies on the simulation of quenching. The subject is covered from the pioneering work up to very recent advances in the field, with special emphasis on future research needs for improving the industrial usage of heat treatment simulations.
