Mühendislik Fakültesi

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Citation - WoS: 32
Citation - Scopus: 43
A 3d Virtual Environment for Training Soccer Referees
(Elsevier Science Bv, 2019) Isler, Veysi; O'Connor, Rory V.; Clarke, Paul M.; Gulec, Ulas; Yilmaz, Murat; 47439
Emerging digital technologies are being used in many ways by and in particular virtual environments provide new opportunities to gain experience on real-world phenomena without having to live the actual real-world experiences. In this study, a quantitative research approach supported by expert validation interviews was conducted to determine the availability of virtual environments in the training of soccer referees. The aim is to design a virtual environment for training purposes, representing a real-life soccer stadium to allow the referees to manage matches in an atmosphere similar to the real stadium atmosphere. At this point, the referees have a chance to reduce the number of errors that they make in real life by experiencing difficult decisions that they encounter during the actual match via using the virtual stadium. In addition, the decisions and reactions of the referees during the virtual match were observed with the number of different fans in the virtual stadium to understand whether the virtual stadium created a real stadium atmosphere for the referees. For this evaluation, Presence Questionnaire (PQ) and Immersive Tendencies Questionnaire (ITQ) were applied to the referees to measure their involvement levels. In addition, a semi-structure interview technique was utilized in order to understand participants' opinions about the system. These interviews show that the referees have a positive attitude towards the system since they can experience the events occurred in the match as a first person instead of watching them from camera as a third person. The findings of current study suggest that virtual environments can be used as a training tool to increase the experience levels of the soccer referees since they have an opportunity to decide about the positions without facing the real-world risks.
A Case Study of Structural Failure of Mounting Systems for Solar Panels from South-Eastern Turkey: An Investigation of Design Parameters under Extreme Weather Events
(2019) Çelik, Gence Genç; Çelik, O.; 101566
One of the biggest demand of growing population, and cornerstone of the socio-economical growth of Nations, Energy is expected today to be Sustainable, Easy to Reach, Economical, and Continuous. As one of the most common and imperative contributors of this Clean Energy Future, Solar Energy in various forms takes a significant role whole around the World. And It shows a great potential particularly for Turkey which imports the majority of its Energy Resources - including Conventional Ones - from Out Sources, to decrease Energy Dependency on Out-of-country Bases and increase awareness to develop competition in New Technology and Production Fields. Based on a Structural Failure Case of Supporting Frames designed for Solar Photovoltaics (PV) in a Solar Power Plant from Turkey, this paper addresses the significance of Local and Site-Specific Investigation of Climate Data to properly decide on Structural Design Parameters -particularly Loads of Snow and Wind- by staying still comformable with National Codes and Standards.
A comparison of iterative Fourier transform algorithms for image quality estimation
(2018) Alsaka, Dina Yaqoob; Arpali, Çağlar; Arpali, Serap Altay; 20809
A comparison was established between two iterative Fourier transform algorithms (IFTAs), such as the original Gerchberg–Saxton (GS) and the mixed-region amplitude freedom (MRAF) algorithms, for the hologram reconstruction of different target images through the full reference image quality estimation (IQE) and pixel homogeneity in the Fourier plane presented theoretically and experimentally. The comparison was applied depending upon both algorithms based on a computer-generated hologram (CGH) implemented utilizing a reflective phase-modulated liquid-crystal spatial light modulator (LC-SLM) to obtain the digital kinoform holograms of the desired intensity distributions. These digital holograms were applied to reconstruct the intensity patterns for 852 nm, which represents a laser beam source. The theoretical and experimental results of the reconstructed patterns obtained using the MRAF algorithm were found to be smoother and better than the patterns obtained using the GS algorithm. Unmodulated light beam (dc term) is removed from the reconstructed patterns attributed to digital kinoform holograms of MRAF algorithm as an alternative to the theoretical and experimental results without using any additional optic equipment at the light path. Moreover, this paper discussed the full reference objective quality estimations, such as mean square error (MSE), peak signal-to-noise ratio (PSNR), structural content (SC), normalized absolute error (NAE), normalized cross correlation (NK), and homogeneity of pixels, through the contrast (Cont) and inverse difference moment (IDM) for numerical and experimental results. According to the two desired intensity distributions processed theoretically and experimentally, the results of MRAF algorithm were found to be in the highly accurate recovered phase, the quality of image was enhanced, and the dc term was decreased. Image quality estimation of full reference objective relay on the feedback algorithms experimental attestation has not been implemented yet.
A complexity reduction method for joint MSVQ
(2016) Özaydın, Selma
A configurable CAN FD controller: architecture and implementation
(IEEE, 2017) Afşin, Mehmet Ertuğ; Schmidt, Klaus Werner; Schmidt, Ece Güran
CAN FD is a new standard which provides fast. data rate while preserving the compatibility with CAN (controller area network). In this paper, a Configurable IP core architecture (A-CAN) which is compatible with the CAN FD standard, is proposed. Different than existing CAN/CAN FD controllers, the numbers and sizes of transmit and receive buffers of A-CAN can be configured in run time. To this end, A-CAN enables the best use of single controller hardware for different applications and enables improving the real time communication performance. A CAN communicates with the host device over SPI without any specific interface requirements. A-CAN is implemented on an FPGA Evaluation Board and its functionally is verified at a rate of 2 Mbps.
A fast and optimal static segment scheduling method for FlexRay v3.0
(IEEE, 2017) Çakmak, Cumhur; Schmidt, Ece Güran; Schmidt, Klaus Werner
We propose a novel and fast frame scheduling method for the Static Segment (SS) of the new in-vehicle network standard FlexRay v3.0 in this paper. The proposed methods assigns frames to the SS using the minimum number of time slots based on an Integer Linear Programming formulation. Different. from the existing method in the literature, the proposed method computes optimal frame schedules within miliseconds.
A new multi-agent decision making structure and application to model-based fault diagnosis problem
(IEEE, 2017) Leblebicioğlu, Kemal; Zengin, Yasin; Schmidt, Klaus Werner
A new hierarchical multi-agent decision-making structure has been proposed. There are two phases of the structure. The first phase is the construction phase where the decision making structure consisting of switching and classification agents is built on the training data set generated by the system scenarios. In construction phase, switching and classification agents are trained and made ready for decision making. In the decision phase, which is the second phase, the class of the new data sample is decided. This process is carried out by the transmission of the data sample to the correct classifier agent by the switching agents and the classification by the classifier agent. The proposed structure is applied to a complex fault identification problem and a successful result is obtained. The structure is also adaptable to other big data decision making problems.
A New Novel Model Proposal For Bond-Slip Behavior Between Angular CFRP Fan Type Anchoraged CFRP Strip and Concrete Surface
(2020) Ghoroubi, Rahim; Mercimek, Ömer; Anıl, Özgür; 306045
In the reinforced concrete, masonry or steel structures should be strengthened or repaired. Carbon fiber reinforced polymers (CFRP) have been widely used for the last 20 years for repairing and strengthening of inadequate earthquake performance of the structures. One of the most important developed design criteria in the retrofit and strengthening details are using CFRP to delay the debonding of the CFRP reinforcement elements. For this reason, the uses of anchors in the reinforcement details developed by using CFRP and also researches on this subject have increased substantially. In the literature, research on bond-slip models developed for fan type CFRP anchors and anchored CFRP strips used in reinforcement details are limited in comparison to non-anchored strips. However, in studies on this subject, anchors are placed at 90o to the axial tensile force applied to the CFRP strips. Axial force-bearing strength and bond-slip models of CFRP strips with the different anchored angle under axial tensile strengths have not been found in the literature. For this reason, an experimental study was carried out and 28 specimens of angled anchored CFRP strip test specimen, which was bonded to the concrete surface, was tested under the influence of axial tensile force with an experimental setup designed by the authors. The variables studied in the experimental study are the CFRP strip width and the fan type CFRP anchor angle placed on the CFRP strip. As a result of the experimental study, an equation was proposed for calculating the bearing strength values of angled anchored CFRP strips and a new proposal for the bond-slip model was developed.
A Novel Analytical Method for Throughput Calculation of Wireless Ad-Hoc Networks Running Different Routing Algorithms
(2018) Preveze, Barbaros; 17573
Because of the increasing number of internet related applications, the role of total router transmission delay became much more important for the service quality. For this purpose, the tunneling techniques have been widely used especially for real time multimedia transmission to have less number of route constructions and to be able to forward each packet at each router without the need of reaching the upper OSI (Open Systems Interconnection) layers. But, in mobile networks, since the network experience with more changes in traffic conditions and node locations, tunnels will be reconstructed for many times and some extra delay will occur to reconstruct these tunnels. In this work, the place of the tunneling algorithm is taken by the well-known MPLS (Multi-Protocol Label Switching) protocol and for confirmation the throughput calculations are made by considering two different routing algorithms, one of which is AEABR algorithm proposed in [1] (shown in [2] that it improves the system throughput w.r.t Fastest path Routing algorithm [3] for various vehicular velocities), and the other one is Fastest Path routing algorithm [3]. In this work a novel analytical method for throughput calculation of wireless ad-hoc networks running aforementioned routing algorıthms is proposed including the effects of extra delay caused by extra Route Reconstructions (RRC).
A Predictive Ground-Motion Model for Turkey and Its Comparison with Recent Local and Global GMPEs
(2011) Cağnan, Zehra; Akkar, Sinan; Gülkan, Polat; 5743
We present a local ground motion prediction equation (GMPE ) for estimating the peak ground-motion values that was derived using the recently compiled Turkish strong motion database . The new GMPE is comparable with the recent global GMPEs in terms of model sophistication and quality of underlying database. Using this equation, we explore the inter-event , inter-station ground motion variability of the recent Turkish strong motion database as well as suitability of some local and global GMPEs for regional seismic hazard assessment analyses. The inter-event error underlines the distinguishing characteristics of few earthquakes, suggesting that the use of local GMPEs can be important especially when specific scenario studies are to be carried out. The inter-station variability allowed us to detect stations with outlier site response and to investigate the goodness of the employed site effect s model. Results also indicate suitability of some global and local GMPEs for use in regional seismic hazard assessments together with the model presented in this study. These should be combined through a logic tree scheme to reduce both aleatory and epistemic uncertainty in local hazard assessments.
A Procurement Auctions-Based Framework for Coordinating Platforms in Humanitarian Logistics
(2013) Ertem, Mustafa Alp; Buyurgan, Nebil; 52460
This chapter focuses on an auction-based procurement framework for single coordinating platforms in humanitarian logistics. It first covers disaster relief operations, humanitarian logistics, and procurement in this context and illustrate many of the issues that make the management and coordination of procurement functions complex and challenging. Then the proposed framework along with the auction model is discussed including the unique design characteristics associated with disaster relief environment. Three-phase approach presents a complete representation of the procurement in humanitarian logistics. Results indicate that the proposed announcement options increase the fill rate. Announcement construction criteria allow coordinating platforms to use varying bundling choices.
A Sequential Coding Approach for Short Length LT Codes over A WGN Channel
(2017) Abdulkhaleq, Nadhir Ibrahim; Gazi, Orhan
Luby Transform (LT) codes which can be considered as one of the first type of rate less codes are introduced to be an efficient erasure code. In such codes a fountain of encoded symbols is continuously transmitted until the successfully delivery of all the data packets. Whenever the receiver collects N noisy encoded symbols the decoding operation starts. Usually belief propagation (BP) algorithm is used to decipher the code and extract the k data symbols. In this paper, short length LT codes are generated using efficient sequential encoding approach (SEA) and performance measurements have been done over additive white Gaussian (A WGN) channel. This coding technique generates its degree in a repeated sequential manner which yields a mutual relation between adjacent codes that will be used in the decoding part. The decoding complexity of the proposed structure is similar to that of the Raptor codes. The simulation results show that the proposed approach has better performance in terms of error floor and successful decoding ratio when compared to LT codes using robust soliton distribution (RSD) and memorybased-RSD (MBRSD) even when supported by belief propagation-pattern recognition (BP-PR) technique.
A sequential coding approach for short length lt codes over awgn channel
(IEEE, 2017) Abdulkhaleq, Nadhir Ibrahim; Gazi, Orhan; 102896
Luby Transform (LT) codes which can be considered as one of the first type of rate less codes are introduced to be an efficient erasure code. In such codes a fountain of encoded symbols is continuously transmitted until the successfully delivery of all the data packets. Whenever the receiver collects N noisy encoded symbols the decoding operation starts. Usually belief propagation (BP) algorithm is used to decipher the code and extract the k data symbols. In this paper, short length LT codes are generated using efficient sequential encoding approach (SEA) and performance measurements have been done over additive white Gaussian (AWGN) channel. This coding technique generates its degree in a repeated sequential manner which yields a mutual relation between adjacent codes that will be used in the decoding part. The decoding complexity of the proposed structure is similar to that of the Raptor codes. The simulation results show that the proposed approach has better performance in terms of error floor and successful decoding ratio when compared to LT codes using robust soliton distribution (RSD) and memory-based-RSD (MBRSD) even when supported by belief propagation-pattern recognition (BP-PR) technique.
A Sociocultural Landmark in Ankara: 96lar Residential Block
(2012) Ürey Uysal, Zeynep Çiğdem
Bu çalışma, Ankaranın önemli bir kentsel simgesi olan 96lar Apartmanını, gelişiminin sosyokültürel önemi bağlamında incelemeyi amaçlamaktadır. Araştırmaların da işaret ettiği gibi 96lar Apartmanı, Ankarada 1950li ve 1980li yıllar arasında etkin olan konut gelişimi ve kooperatifçilik süreçlerinin etkisinde gelişen kendine özgü mimari planlama anlayışı ve yapım süreci dolayısıyla Ankara konut mimarisi bağlamında önemli bir yere sahip olmuştur. 96lar Apartmanının sosyokültürel gelişimini ve mimari oluşumunu döneminin kültürel, sosyal ve mimari gelişmeleri ışığında analiz etmeyi amaçlayan bu çalışma, sırasıyla Ankaradaki 1950li ve 1980li yıllar arasındaki konut üretiminden, 96lar Apartmanının bu bağlam içerisindeki yerinden, planlama anlayışı ve mimari özelliklerinden ve Modern Mimariye yaptığı referanslardan bahsedecektir.
About nanometer sized analogues of basic electronic and optical components
(IEEE, 2008) Quandt, Alexander; Özdoğan, Cem; Ferrari, Maurizio; Speranza, Giorgio; 40569
We discuss a downsizing of optical components into the nanometer range. It presupposes the substitution of photons by ballistic electrons, but it also requires a simple and robust concept to assemble the analogues of basic electronic and optical components on such a tiny length scale. Here, one of the most promising candidate schemes employs graphene as a basic nanosubstrate. We elucidate the suggested behaviour of graphene as an electronic metamaterial [1], and show that other desired electronic or optical functionalities may be obtained through a patterning with sub-nanometer sized boron clusters [2].
Citation - Scopus: 4
Abstract Conceptual Database Model Approach
(2013) Çağıltay, Nergiz; Çaĝiltay, N.E.; Topalli, D.; Tokdemir, Gül; Aykaç, Y.E.; Tokdemir, G.; 17411; Yazılım Mühendisliği; Bilgisayar Mühendisliği
One of the main objectives of the software engineers is to provide software related solutions for social problems and to increase the availability of social welfare. In that sense, the quality of the software is directly related to address the users' needs and their level of satisfaction. To reflect user requirements to the software processes, the correct design of the database model provides a critical stage during software development. Database design is a fundamental tool for modeling all the requirements related to users' data. The possible faulty conditions in database design have adverse effects on all of the software development processes. The possible faulty conditions can also cause continuous changes in the software and the desired functionality of the targeted system which may result in user dissatisfaction. In this context, reflecting the user requirements accurately in the database model and understanding of the database model correctly by every person involved in the software development process is the factor that directly affects the success of software systems' development. In this study, a two-stage conceptual data modeling approach is proposed to reduce the level of complexity, to improve the understandability of database models and to improve the quality of the software. This study first describes the proposed two-stage conceptual data modeling. Than the proposed method's impact on software engineers' comprehension is also investigated and the results are compared with the degree of complexity of the related conceptual data models. Results of this study show that, the proposed two-stage conceptual modeling approach improves the understanding levels of software engineers and eliminated possible defects in this stage. © 2013 The Science and Information Organization.
Citation - Scopus: 7
Abstraction-Based Control for Not Necessarily Closed Behaviours
(IFAC Secretariat, 2011) Moor, T.; Schmidt, K.; Wittmann, T.
This paper addresses abstraction-based supervisory control for plant and specification behaviours that are not necessarily ω-closed, i.e. plant behaviours that exhibit eventuality properties and specifications that impose eventuality properties on the closed loop. Technically, the core idea is to combine results from previous work on abstraction-based supervision of input-output behaviours with results on supervisory control of ω-languages. As our main result, we identify a controllability condition for the plant, that ensures a nonblocking closed-loop behaviour with a controller that has been obtained for a plant abstraction. © 2011 IFAC.
Abstraction-Based Modeling and Control For Reconfigurable Machine Tools (RMT)
(2014) Khalid, Harith M.; Schmidt, Klaus
Citation - Scopus: 5
Abstraction-Based Supervisory Control for Recon-Gurable Manufacturing Systems
(IFAC Secretariat, 2013) Khalid, H.M.; Kirik, M.S.; Schmidt, K.W.; 271229
Reconfiguration control for discrete event systems (DES) is concerned with the realization of different system configurations by modification of the supervisory control loop. In this paper, we study the reconfiguration supervisor design for reconfigurable manufacturing systems (RMS) that comprise multiple components. We construct a modular supervisor for each configuration and system component in order to realize each active configuration and to quickly change between configurations. Different from the existing literature that is focused on monolithic design, our method is abstraction-based, and, hence applicable to large-scale DES. © 2013 IFAC.
Citation - WoS: 12
Citation - Scopus: 17
Abstraction-Based Verification of Codiagnosability for Discrete Event Systems
(Pergamon-elsevier Science Ltd, 2010) Schmidt, K.
In this paper, we investigate the verification of codiagnosability for discrete event systems (DES). That is, it is desired to ascertain if the occurrence of system faults can be detected based on the information of multiple local sites that partially observe the overall DES. As an improvement of existing codiagnosability tests that resort to the original DES with a potentially computationally infeasible state space, we propose a method that employs an abstracted system model on a smaller state space for the codiagnosability verification. Furthermore, we show that this abstraction can be computed without explicitly evaluating the state space of the original model in the practical case where the DES is composed of multiple subsystems. (c) 2010 Elsevier Ltd. All rights reserved.

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