Sürdürülebilir Yeşil Kampüs Koleksiyonu / Sustainable Green Campus Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7755

Browse

Filters

2003 - 200952010 - 20199

Settings

Department: search.filters.department.İzmir Institute of Technology. Mechanical Engineering

Search Results

Now showing 1 - 10 of 14
  • Article
    Citation - WoS: 6
    Citation - Scopus: 7
    Aerodynamic Optimization of Through-Flow Design Model of a High By-Pass Transonic Aero-Engine Fan Using Genetic Algorithm
    (SAGE Publications Inc., 2018) Kor, Orçun; Acarer, Sercan; Özkol, Ünver
    This study deals with aerodynamic optimization of a high by-pass transonic aero-engine fan module in a through-flow inverse design model at cruise condition. To the authors’ best knowledge, although the literature contains through-flow optimization of the simplified cases of compressors and turbines, an optimization study targeting the more elaborate case of combined transonic fan and splitter through-flow model is not considered in the literature. Such a through-flow optimization of a transonic fan, combined with bypass and core streams separated by an aerodynamically shaped flow splitter, possesses significant challenges to any optimizer, due to highly non-linear nature of the problem and the high number of constraints, including the fulfillment of the targeted bypass ratio. It is the aim of this study to consider this previously untouched area in detail and therefore present a more sophisticated and accurate optimization environment for actual bypass fan systems. An in-house optimization code using genetic algorithm is coupled with a previously developed in-house through-flow solver which is using a streamline curvature technique and a set of in-house calibrated empirical models for incidence, deviation, loss and blockage. As the through-flow models are the backbone of turbomachinery design, and great majority of design decisions are taken in this phase, such a study is assessed to result in significant guidelines to the gas turbine community.
  • Article
    Active Fault Tolerant Control of a Wind Farm System
    (IFAC Secretariat, 2018) Simani, Silvio; Turhan, Cihan
    In order to enhance the 'sustainability’ of offshore wind farms, thus skipping unplanned maintenance operations and costs, that can be important for offshore systems, the earlier management of faults represents the key point. Therefore, this work studies the development of an adaptive sustainable control scheme with application to a wind farm benchmark consisting of nine wind turbine systems. They are described via their nonlinear models, as well as the wind and wake effects among the wind turbines of the wind park. The fault tolerant control strategy uses the recursive estimation of the faults provided by nonlinear estimators designed via a nonlinear differential algebraic tool. This aspect of the study, together with the more straightforward solution based on a data-driven scheme, is the key issue when on-line applications are proposed for a viable implementation of the proposed solutions.
  • Book Part
    Control Methods for a Teleoperated Endoscope Robot
    (Springer Verlag, 2019) Işıtman, Oğulcan; Dede, Mehmet İsmet Can
    In this study, control of a endoscope robot for the pituitary gland surgery is presented. This co-worker robot has non-backdrivable actuation system with external brakes on the actuators. Since it is required to move in a constrained environment, which is the inside the nostrils in this case, modifications are required for the motion controller. In order to provide safe procedure, the maximum force and torque limits are defined for the real surgical case by using human cadaver head. By considering these limits and application specific requirements, a compliance controller is proposed and experimentally tested.
  • Article
    Citation - WoS: 12
    Citation - Scopus: 12
    Geometrical Analysis of a Continuously Variable Transmission System Designed for Human-Robot Interfaces
    (Elsevier, 2019) Mobedi, Emir; Dede, Mehmet İsmet Can
    New robotic systems are placed out of their constrained workspaces in order to work alongside humans. Consequently, these applications call for robots monitoring and regulating physical human-robot interaction. These robots’ mechanical compliance should be varied when they are in physical contact with the human or their changing environments. This compliance variation can be achieved in a variety of ways. However, one common idea is the variation of joint stiffness mechanically, electromechanically or by control. The solution presented in this paper is an electromechanical way of varying the joint stiffness. Among the electromechanical methods for varying the joint stiffness, continuously variable transmission (CVT) systems can be used in human-robot interfaces if a set of design criteria are met. These criteria include backdrivability, independent output position and stiffness variation, shock absorbing and low mass/inertia. In this paper, a novel two-cone CVT design with a double spherical transmission element is introduced by taking into account the abovementioned criteria. Additionally, design parameters are identified via carrying out a geometrical analysis of this new CVT system.
  • Conference Object
    Citation - WoS: 1
    Citation - Scopus: 1
    Adaptive Signal Processing Strategy for a Wind Farm System Fault Accommodation
    (Institute of Electrical and Electronics Engineers, 2018) Simani, Silvio; Turhan, Cihan
    In order to enhance the 'sustainability' of offshore wind farms, thus skipping unplanned maintenance operations and costs, that can be important for offshore systems, the earlier management of faults represents the key point. Therefore, this work studies the development of an adaptive sustainable control scheme with application to a wind farm benchmark consisting of nine wind turbine systems. They are described via their nonlinear models, as well as the wind and wake effects among the wind turbines of the wind park. The fault tolerant (i.e., sustainable) control strategy uses the recursive estimation of the faults provided by nonlinear estimators designed via a nonlinear differential algebraic tool. These estimators are not affected by the model uncertainty and the wake effects among the wind turbines. This work exploits also a data-driven method used for estimating the analytical form of these disturbance functions, which are employed for obtaining the nonlinear fault reconstructors. Note that purely analytic approaches, where the model nonlinearity and the disturbance decoupling features are directly taken into account, may lead to more complex design tools. This aspect of the study, together with the more straightforward solution based on a data-driven scheme, is the issue when online applications are proposed for a viable implementation of the proposed solutions. The benchmark is exploited to verify the features of the developed strategies with respect to various fault situations and unavoidable model-reality mismatch.
  • Conference Object
    Citation - Scopus: 3
    Design and Simulation of a Novel Hybrid Leg Mechanism for Walking Machines
    (Springer Verlag, 2018) Demirel, Murat; Carbone, Giuseppe; Ceccarelli, Marco; Kiper, Gökhan
    This paper introduces a novel hybrid structure design that is composed of rigid links and cables for a robotic leg with static walking. The proposed mechanism is characterized by actuated hip joints, passive knee joints and an actuated prismatic foot joint. The foot is the moving platform of the proposed mechanism which possesses pure translational motion due to the passive parallelograms with cables. Kinematic analysis has been worked out for evaluating a typical human-like gait trajectory. A 3-D model has been developed and simulation are made in SolidWorks® environment. Simulation results show that the proposed mechanism is able to perform an ovoid walking cycle of a foot point and the computed actuator torques and forces are in a feasible range for a low-cost and easy-operation design. The simulation results will be used for a prototype construction in a future work.
  • Article
    Citation - WoS: 6
    Citation - Scopus: 7
    An Entropy-Based Analysis of Lane Changing Behavior: An Interactive Approach
    (Taylor and Francis Ltd., 2017) Koşun, Çağlar; Özdemir, Serhan
    Objectives: As a novelty, this article proposes the nonadditive entropy framework for the description of driver behaviors during lane changing. The authors also state that this entropy framework governs the lane changing behavior in traffic flow in accordance with the long-range vehicular interactions and traffic safety. Methods: The nonadditive entropy framework is the new generalized theory of thermostatistical mechanics. Vehicular interactions during lane changing are considered within this framework. The interactive approach for the lane changing behavior of the drivers is presented in the traffic flow scenarios presented in the article. According to the traffic flow scenarios, 4 categories of traffic flow and driver behaviors are obtained. Through the scenarios, comparative analyses of nonadditive and additive entropy domains are also provided. Results: Two quadrants of the categories belong to the nonadditive entropy; the rest are involved in the additive entropy domain. Driving behaviors are extracted and the scenarios depict that nonadditivity matches safe driving well, whereas additivity corresponds to unsafe driving. Furthermore, the cooperative traffic system is considered in nonadditivity where the long-range interactions are present. However, the uncooperative traffic system falls into the additivity domain. The analyses also state that there would be possible traffic flow transitions among the quadrants. This article shows that lane changing behavior could be generalized as nonadditive, with additivity as a special case, based on the given traffic conditions. Conclusions: The nearest and close neighbor models are well within the conventional additive entropy framework. In this article, both the long-range vehicular interactions and safe driving behavior in traffic are handled in the nonadditive entropy domain. It is also inferred that the Tsallis entropy region would correspond to mandatory lane changing behavior, whereas additive and either the extensive or nonextensive entropy region would match discretionary lane changing behavior. This article states that driver behaviors would be in the nonadditive entropy domain to provide a safe traffic stream and hence with vehicle accident prevention in mind.
  • Article
    Citation - WoS: 4
    Citation - Scopus: 4
    Extending Model-Mediation Method To Multi-Degree Teleoperation Systems Experiencing Time Delays in Communication
    (Cambridge University Press, 2017) Uzunoğlu, Emre; Dede, Mehmet İsmet Can
    SUMMARY In this study, a bilateral teleoperation control algorithm is developed in which the model-mediation method is integrated with an impedance controller. The model-mediation method is also extended to three-degrees-of-freedom teleoperation. The aim of this controller is to compensate for instability issues and excessive forcing applied to the slave environment stemming from time delays in communication. The proposed control method is experimentally tested with two haptic desktop devices. Test results indicate that stability and passivity of the bilateral teleoperation system is preserved under variable time delays in communication. It is also observed that safer interactions of the slave system with its environment can be achieved by utilizing an extended version of the model-mediation method with an impedance controller.
  • Conference Object
    Citation - WoS: 9
    Citation - Scopus: 13
    Design of a Haptic Device for Teleoperation and Virtual Reality Systems
    (Institute of Electrical and Electronics Engineers Inc., 2009) Dede, Mehmet İsmet Can; Selvi, Özgün; Bilgincan, Tunç; Kant, Yalkın
    Haptics technology has increased the precision and telepresence of the teleoperation and precision of the in-house robotic applications by force and surface information feedback. Force feedback is achieved through sending back the pressure and force information via a haptic device as the information is created or measured at the point of interest. In order to configure such a system, design, analysis and production processes of a haptic device, which is suitable for that specific application, becomes important. Today, haptic devices find use in assistive surgical robotics and most of the teleoperation systems. These devices are also extensively utilized in simulators to train medical and military personnel. The objective of this work is to design a haptic device with a new structure that has the potential to increase the precision of the robotic operation. Thus, literature is reviewed and possible robot manipulator designs are investigated to increase the precision in haptics applications. As a result of the investigations, conceptual designs are developed. Ultimately, final design is selected and produced after it is investigated in computer-aided- design (CAD) environment and its kinematic and structural analyses are carried out.
  • Article
    Citation - WoS: 5
    Citation - Scopus: 7
    Hydrogeochemistry and Environmental Properties of Geothermal Fields. Case Study: Balçova, Izmir-Turkey
    (Taylor and Francis Ltd., 2012) Çakın, Ayça; Gökçen Akkurt, Gülden; Eroğlu, Ahmet Emin; Baba, Alper
    Balcova Geothermal Field hosts the largest geothermal district heating system of Turkey and a number of shallow groundwater wells that are used for irrigation of the agricultural activities. The present study aims to assess the influence of geothermal fluid on groundwater by determining the hydrogeochemical properties of the water resources. A sampling program was conducted for 10 months and samples were collected from geothermal and groundwater wells including re-injected fluid. Trace and major elements, and the types of waters were determined. The results of groundwater analysis showed that the concentrations of some toxic species, such as arsenic, boron, and fluoride, exceeded the limits of drinking water standards set by TSE, EPA, and WHO.