Mechanical Engineering / Makina Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/4129

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Access type: Open accessInstitution Author: search.filters.institutionAuthor.Özdemir, Serhan

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Now showing 1 - 10 of 23
  • Article
    Casting the Swarms Problem in the Ensembles Context
    (Çukurova Üniversitesi, 2016) Kok, Çağatay; Çellek, Seven Burçin; Koşun, Çağlar; Özdemir, Serhan
    Sürü robotları yüzlerce farklı şekilde modellenmiştir. Kalabalık olmaları sürülerin bir özelliğidir. Sayılamayacak kadar çok sayıya ulaştıklarında, termo-istatiksel mekanik devreye girebilir. Yazarlar bu avantajı kullanarak sürü robotları için evrensel istatistik oluşturmak istediler. Üç temel topluluk açıklandı ve formüle edildi. Sürüler izole edildiklerinde mikrokanonik uyum ortama hakim olurken, ortama av veya avcı girişi olur ise, duruma bağlı olarak değişimler gözlemlenir. Bu yüzden formulasyonlar ve geçişler şarta bağlıdır. Son olarak gözlemlenen olasılıklar tartışıldı
  • Conference Object
    Citation - WoS: 1
    Citation - Scopus: 6
    The Use of Chipless Sensors With Rfid for Condition Monitoring
    (Institute of Electrical and Electronics Engineers Inc., 2018) Biliç, H. Gökay; Büyüköztekin, Tarık; Özdemir, Serhan
    This paper presents the development phases and overview of developing research in the area of RFID condition monitoring, focusing on chipless sensors especially use in strain and temperature sensing applications. Classification of RFID sensors and smart material fundamentals are reviewed. The compact and feasible design of RFID sensors will be considered, as well as with the effect of different material usage. Finally, the use of chipless sensors with different condition monitoring applications and their challenges are investigated.
  • Article
    Power transmission entropy
    (Inderscience Enterprises Ltd., 2008) Özdemir, Serhan
    Mechanical transmissions have been characterised traditionally by their transmission efficiencies. This is given by the ratio of the output to the input of the transmitted power. Unfortunately, the power transmission phenomenon is slightly more complex than that. As any designer would agree, each of these transmission localities is a source of uncertainty. Once formulated, this statement of uncertainty would reflect the designer's trust in the transmission. By virtue of the proposed approach, power transmission is no longer a deterministic entity but becomes a probabilistic one. This paper discusses the overlooked uncertainty inherent in every transmission.
  • Article
    Local Sparse Coding Control of Cvpsts
    (Inderscience Enterprises, 2005) Özdemir, Serhan
    This paper discusses simulations of a control scheme based on locally sparse coded networks (CMACs) for a novel previously proposed continuously variable transmission (CVT), a hybrid continuously variable power split transmission (CVPST) (Osdemir and Schueller, 2002). Automotive transmissions match the speed and the torque of the power source to the speed and torque requirements of the load. Properly designed CVTs have shown potential to improve efficiency and performance. The main advantage of CMACs is fast computation because of their simple operational principles. Simulation results have shown that memory contents either reach a stable limit cycle or an attractor based on the selection of network parameters and the training method. Both online and offline training are possible.
  • 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: 3
    Citation - Scopus: 3
    Determining the Complexity of Multi-Component Conformal Systems: a Platoon-Based Approach
    (Elsevier Ltd., 2017) Koşun, Çağlar; Özdemir, Serhan
    Many systems in nature and engineering are composed of subsystems. These subsystems may be formed in a linear, planar or spatial array. A typical example of these formations is a chain of vehicles known as platoon formation in traffic flow. Platoon formation of vehicles is a linear or planar formation of vehicles where a certain and a constant headway, and sideway if applicable, is provided in between every and each one of them. It is argued in this paper that a well-automated platoon formation of vehicles is an extreme case of conformity. During this transformation from a many degrees of freedom formation to a solid object, Tsallis q value is computed to be ranging from one extreme case of q=3 to the other where q=1, when classified in terms of inverse temperatures of clearance fluctuations. At one extreme of q=3, one observes unbounded fluctuations in clearance fluctuations so that inverse temperature distributions approach a Dirac delta at the origin. At the other extreme of q=1, fluctuations in clearance tend to zero asymptotically, where a solid structure of agents (vehicles) emerges. The transition from q=3 to q=1 is investigated through synthetic and experimental clearance fluctuations between the cars. The results show that during the transition from q=3 to q=1, the platoon loses its many degrees of freedom (dof) of motion until a solid single object emerges. Authors assert that the Tsallis q value of a platoon of vehicles is limited to 3>q<1.
  • Article
    Citation - WoS: 14
    Citation - Scopus: 15
    A Superstatistical Model of Vehicular Traffic Flow
    (Elsevier Ltd., 2016) Koşun, Çağlar; Özdemir, Serhan
    In the analysis of vehicular traffic flow, a myriad of techniques have been implemented. In this study, superstatistics is used in modeling the traffic flow on a highway segment. Traffic variables such as vehicular speeds, volume, and headway were collected for three days. For the superstatistical approach, at least two distinct time scales must exist, so that a superposition of nonequilibrium systems assumption could hold. When the slow dynamics of the vehicle speeds exhibit a Gaussian distribution in between the fluctuations of the system at large, one speaks of a relaxation to a local equilibrium. These Gaussian distributions are found with corresponding standard deviations 1/β. This translates into a series of fluctuating beta values, hence the statistics of statistics, superstatistics. The traffic flow model has generated an inverse temperature parameter (beta) distribution as well as the speed distribution. This beta distribution has shown that the fluctuations in beta are distributed with respect to a chi-square distribution. It must be mentioned that two distinct Tsallis q values are specified: one is time-dependent and the other is independent. A ramification of these q values is that the highway segment and the traffic flow generate separate characteristics. This highway segment in question is not only nonadditive in nature, but a nonequilibrium driven system, with frequent relaxations to a Gaussian.
  • Conference Object
    The Influence of the Surface Topography of Distributed Sensor Networks on Perception
    (CSREA Press, 2012) Özkan, Özün Beyhan; Tosun, Öykü Ece; Arslan, Arda; Gençer, İsmail Cenk; Özçetin, Mustafa; Serindağ, Yelda; Memiş, Korhan; Özdemir, Serhan
    This work investigates the effects of surface topography of the distributed sensor networks on perception through the differences in sensor readings. Compound eyes are found in some insects and crustaceans. Lateral inhibition is a biological signal processing which can increase contrast, enhancing perception. It is known that eye convexity helps increase field of view (FOV). A series of experiments were carried out to understand the effect of surface topography on local contrast gradient. Two sets of sensor networks of 5 × 5 were constructed. In the first network the board holding the sensors was a flat circuit board, whereas the second one was given a radius of curvature of roughly 30 cm. All readings were recorded in a dark chamber. Sensor networks were illuminated by a light source whose coordinates could be adjusted. Results are tabulated. It is seen that eye convexity in compound eyes improves perception, as well as FOV.
  • Article
    Citation - Scopus: 1
    Cost Effective Localization in Distributed Sensory Networks
    (Elsevier Ltd., 2011) Coşkun, Anıl; Sevil, Hakkı Erhan; Özdemir, Serhan
    The most important mechanism to occur in biological distributed sensory networks (DSNs) is called lateral inhibition, (LI). LI relies on one simple principle. Each sensor strives to suppress its neighbors in proportion to its own excitation. In this study, LI mechanism is exploited to localize the unknown position of a light source that illuminated the photosensitive sensory network containing high and low quality sensors. Each photosensitive sensor was then calibrated to accurately read the distance to the light source. A series of experiments were conducted employing both quality sensors. Low quality array was allowed to take advantage of LI, whereas the high quality one was not. Results showed that the lateral inhibition mechanism increased the sensitivity of inferior quality sensors, giving the ability to make the localization as sensitive as high quality sensors do. This suggests that the networks with multitude of sensors could be made cost-effective, were these sensory networks equipped with LI.
  • Article
    Citation - WoS: 6
    Citation - Scopus: 7
    Classification of Manipulators of the Same Origin by Virtue of Compactness and Complexity
    (Elsevier Ltd., 2011) Gezgin, Erkin; Özdemir, Serhan
    This work deals with a classification method that employs concepts such as complexity and compactness. The idea is to classify manipulators, or any other mechanism for that matter, of the same origin, based on the geometry of the joints, the tasks performed by the joints, the efficiency and the manufacturing cost to generate the specified efficiency. It is known that successive units on a single branch create individual uncertainties that affect the eventual quality of the performed operation [1]. An entropic expression quantifies this uncertainty in terms of the number of links and the unit effectiveness. The concepts of compactness and complexity have been formulated, and these concepts are explained through serial and parallel manipulators with varying parameters. Eventually, a cost function is created which is a function of complexity, uncertainty and the manufacturing cost. A worked example on M = 6 Stewart-Gough platform is given how this cost function could be taken advantage of when deciding an initial manipulator. A genetic algorithm is used for the optimization of the cost function, where the results are tabulated.