WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Citation - WoS: 4Citation - Scopus: 3A new hybrid CVT design: CVPSTs(Inderscience Enterprises Ltd., 2002) Özdemir, Serhan; Schueller, JohnAutomotive transmissions match the speed and the torque of the power source to the speed and torque requirements of the load. Properly designed continuously variable transmissions (CVTs) have shown promise to improve efficiency and performance. This work discusses some existing CVTs and proposes a new hybrid continuously variable power split transmission (CVPST). The speed relationships are analysed in power split and power recirculation mechanisms, the problem of geared neutral phenomenon with recirculating transmissions are identified and these two separate issues are left out as a topic for another paper. A new 'all-in-one' CVPST transmission incorporating power split and power recirculation is proposed.Conference Object Citation - WoS: 1Citation - Scopus: 6The Use of Chipless Sensors With Rfid for Condition Monitoring(Institute of Electrical and Electronics Engineers Inc., 2018) Biliç, H. Gökay; Büyüköztekin, Tarık; Özdemir, SerhanThis 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, SerhanMechanical 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, SerhanThis 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: 6Citation - Scopus: 7An Entropy-Based Analysis of Lane Changing Behavior: An Interactive Approach(Taylor and Francis Ltd., 2017) Koşun, Çağlar; Özdemir, SerhanObjectives: 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: 3Citation - Scopus: 3Determining the Complexity of Multi-Component Conformal Systems: a Platoon-Based Approach(Elsevier Ltd., 2017) Koşun, Çağlar; Özdemir, SerhanMany 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 - Scopus: 1Cost Effective Localization in Distributed Sensory Networks(Elsevier Ltd., 2011) Coşkun, Anıl; Sevil, Hakkı Erhan; Özdemir, SerhanThe 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: 6Citation - Scopus: 7Classification of Manipulators of the Same Origin by Virtue of Compactness and Complexity(Elsevier Ltd., 2011) Gezgin, Erkin; Özdemir, SerhanThis 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.Article Citation - WoS: 2Citation - Scopus: 2Trait-based heterogeneous populations plus (TbHP+) genetic algorithm(Elsevier Ltd., 2009) Tayfur, Gökmen; Sevil, Hakkı Erhan; Gezgin, Erkin; Özdemir, SerhanThis study developed a variant of genetic algorithm (GA) model called the trait-based heterogeneous populations plus (TbHP+). The developed TbHP+ model employs a memory concept in the form of immunity and instinct to provide the populations with a more efficient guidance. Also, it has an ability to vary the number of individuals during the search process, thus allowing an automatic determination of the size of the population based on the individual qualities such as character fitness and credit for immunity. The algorithm was tested against the classical GA model in convergence and minimum error performance. For this purpose, 5 different mathematical functions from the literature were employed. The selected functions have different topological characteristics, ranging from simple convex curves with 2 variables to complex trigonometric ones having several hilly shapes with more than 2 variables. The developed model and the classical GA model were applied to finding the global minima of the functions. The comparison of the results revealed that the developed TbHP+ model outperformed the classical GA in faster convergence and minimum errors, which may be explained by the adaptive nature of the new paradigm.Article Citation - WoS: 3Citation - Scopus: 2Prediction of Microdrill Breakage Using Rough Sets(Cambridge University Press, 2011) Sevil, Hakkı Erhan; Özdemir, SerhanThis study attempts to correlate the nonlinear invariants’ with the changing conditions of a drilling process through a series of condition monitoring experiments on small diameter (1 mm) drill bits. Run-to-failure tests are performed on these drill bits, and vibration data are consecutively gathered at equal time intervals. Nonlinear invariants, such as the Kolmogorov entropy and correlation dimension, and statistical parameters are calculated based on the corresponding conditions of the drill bits. By intervariations of these values between two successive measurements, a drop–rise table is created. Any variation that is within a certain threshold (+-20% of the measurements in this case) is assumed to be constant. Any fluctuation above or below is assumed to be either a rise or a drop. The reduct and conflict tables then help eliminate incongruous and redundant data by the use of rough sets (RSs). Inconsistent data, which by definition is the boundary re-gion, are classified through certainty and coverage factors. By handling inconsistencies and redundancies, 11 rules are ex-tracted from 39 experiments, representing the underlying rules. Then 22 new experiments are used to check the validity of the rule space. The RS decision frame performs best at predicting no failure cases. It is believed that RSs are superior in dealing with real-life data over fuzzy set logic in that actual measured data are never as consistent as here and may dominate the monitoring of the manufacturing processes as it becomes more widespread.