Sürdürülebilir Yeşil Kampüs Koleksiyonu / Sustainable Green Campus Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7755
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Article Citation - WoS: 10Citation - Scopus: 26Mobile Join Operators for Restricted Sources(Hindawi Publishing Corporation, 2005) Özakar, Belgin; Morvan, Franck; Hameurlain, AbdelkaderWe consider the problem of query execution when there is limited access to the relations, i.e. when binding patterns require values to be specified in order to get data from the relation. This problem is common in virtual data integration systems where there are heterogeneous sources with various restricted access patterns and query capabilities. Another problem is the lack of the statistical information about the sources and occurrence of unpredictable events. We introduce two mobile join operators, MDJoin and SMDJoin which are designed for restricted sources and implemented using ‘mobile agents’ in order to benefit from their autonomous and reactive characteristics. Mobile operators of restricted sources are capable to deal with restricted sources and react to the variations between the compile-time estimations and run-time computations of data during query execution. The difference between the two new query operators lies in their level of adaptation ability to the execution environment. Performance results show that mobile agent-based approach at operator level can lead to a significant reduction in response time with restricted sources.Master Thesis B and Se Transport Modeling in Saturated/Unsaturated Zones(Izmir Institute of Technology, 2002) Yüreklitürk, O. Emin; Tayfur, GökmenThere has been renewed interest in the application of models to the transport of non-point source pollutants. However, very little work has been done to evaluate the performance of a functional transient-state model for the transport of a reactive solute over an extensive study period. This research consists of mathematical modeling to simulate water flow, boron and selenium transport through soil in tile-drained croplands.For Boron part a mathematical model was developed to simulate non-conservative boron transport. The dynamic two-dimensional finite element model simulates water flow and boron transport in saturated-unsaturated soil system, including boron sorption and boron uptake by root-water extraction. Two different models have been employed for the sorption of boron. Similarly, for selenium part a finite element model is developed to simulate species of selenium transport in two dimensions in saturated/unsaturated zones. The model considers water, selenate, selenite and selenomethionine uptake by plants. It also considers oxidation/reduction, volatilization, and chemical and biological transformations of selenate, selenite, and selenomethionine. Comparison of boron transport model results with observed data is satisfactory. The model employed with Langmuir isotherm was found to give slightly better simulation results when compared with the model employed with Freundlich. The sensitivity analysis results indicate that the irrigation scheduling and the irrigation water quality are very important parameters for boron accumulation in the soil. Also the adsorption isotherm parameters, which reflect us the soil properties, are found to be important for the boron movement in the soil. Comparison of selenium transport model with observed data is not quite satisfactory in accuracy when compared with the model for boron transport. This may be the result of the complexity of the mechanisms affecting the selenium transport in soil. There are too many parameters, and due to the errors depending on the parameters, the total error for the estimation of the total selenium increases.Conference Object Citation - Scopus: 1Implementation of Partial Synchronization of Different Chaotic Systems by Field Programmable Gate Array(Institute of Electrical and Electronics Engineers Inc., 2009) Eroğlu, Can; Savacı, Ferit AcarIn this study, the synchronization of the master-slave systems has been achieved and implemented on Field Programmable Gate Array (FPGA). In this paper, the master system and the slave system have been chosen as Lorenz and Rossler systems, respectively. The feedback control rule has been derived by feedback linearization method. By feedback linearization, the coordinate transformation has been achieved then the control command for synchronization has been obtained. In order to implement designed synchronized system, Matlab Simulink design of the system has been translated to Xilinx System Generator design to generate Very-High-Speed Integrated Circuits Hardware Description Language (VHDL) code which is used to produce bitstream file. By Xilinx Integrated Software Environment (ISE) program, VHDL code is converted to bitstream file which has been embedded into FPGA by Field Upgradeable Systems Environment (FUSE). Finally, the designed synchronized system has been observed on the HP 54540C oscilloscope.Article Citation - WoS: 2Citation - Scopus: 4Genotyping of Various Arcobacter Species Isolated From Domestic Geese by Randomly Amplified Polymorphic Dna (rapd) Analysis(M. & H. Schaper, 2008) Atabay, Halil İbrahim; Ünver, Ahmet; Otlu, Salih; Kalaycıoğlu, Atila TanerThe present study was undertaken to genotype Arcobacter (A.) butzleri, A. cryaerophilus and A. skirrowii isolates from domestic geese from three different flocks in Turkey. Fifteen Arcobacter isolates were analysed to determine the RAPD profiles based on the amplified DNA fragment patterns using a universal primer for genotyping. 7 A. cryaerophilus, 2 A. butzleri and 6 A. skirrowii isolates produced 6, 2 and 3 distinct profiles, respectively. The isolates of the same patterns originated from the same flocks. The findings of the present study may support previous reports of the existence of a large degree of heterogeneity among Arcobacter isolates. Observation of such levels of genetic diversity may suggest that there are multiple contamination sources in the environment and/or the determined genotypes may have undergone genetic rearrangements. This first report of genotyping of various Arcobacter species isolated from healthy geese is expected to improve the understanding of the ecology and epidemiology of this emerging pathogen.Conference Object Citation - WoS: 7Citation - Scopus: 12Time Synchronization Algorithms Based on Timing-Sync Protocol in Wireless Sensor Networks(Institute of Electrical and Electronics Engineers Inc., 2008) Kulaklı, Ali Burak; Erciyeş, KayhanWireless Sensor Networks(WSN) are large scale networks of sensors running on wireless environment. For an application running on a WSN, gathered data by the sensors are time critical in most of the cases. However, almost all the nodes suffer from a problem named clock drift. This problem causes clock difference among nodes as time goes because the processors do not run exactly at the same speed. There are many proposed solutions to remedy this problem. TPSN (Timing-sync Protocol for Sensor Networks) is one of the effective protocols proposed to synchronize sensor networks. In this paper, we propose enhancements over TPSN to synchronize nodes in a wireless sensor network more effectively with a lower message complexity and higher precision.Conference Object Control of Teleoperation Systems Operating Under Communication Line Failures(Institute of Electrical and Electronics Engineers Inc., 2008) Dede, Mehmet İsmet Can; Tosunoğlu, SabriAbstract While the robots gradually become a part of our daily lives, they already play vital roles in many critical operations. Some of these critical tasks include surgeries, battlefield operations, and tasks that take place in hazardous environments or distant locations such as space missions. In most of these tasks, remotely controlled robots are used instead of autonomous robots. This special area of robotics is called teleoperation. Teleoperation systems must be reliable when used in critical tasks; hence, all of the subsystems must be dependable even under a subsystem or communication line failure. Teleoperation controllers are designed to compensate for instabilities due to communication time delays. Modifications to the existing controllers are proposed to configure a controller that is reliable under communication line failures. Experimental studies are then conducted on limited-and unlimited-workspace teleoperation systems to verify the efficiency of the controllers proposed for each system.Conference Object Citation - WoS: 5Citation - Scopus: 6Set-Point Navigation of a Redundant Robot in Uncertain Environments Using Finite Range Sensors(Institute of Electrical and Electronics Engineers Inc., 2008) Kapadia, Apoorva; Tatlıcıoğlu, Enver; Dawson, Darren M.In this work, control of redundant robot manipulators in an uncertain environment is considered. The manipulator is equipped with finite range sensors to detect obstacles in its workspace. A navigation functionbased kinematic controller is proposed to ensure the regulation of the end-effector to a desired set-point while the entire manipulator simultaneously avoids the obstacle points detected by the sensors. A joint-space controller is then utilized to ensure asymptotic tracking of the desired jointspace trajectory.Article Citation - WoS: 50Citation - Scopus: 53Nanoscale Oxide Growth on Al Single Crystals at Low Temperatures: Variable Charge Molecular Dynamics Simulations(American Physical Society, 2006) Hasnaoui, A.; Politano, O.; Salazar, J. M.; Aral, GürcanWe investigate the oxidation of aluminum low-index surfaces [(100), (110), and (111)] at low temperatures (300-600 K) and three different gas pressure values. We use molecular dynamics (MD) simulations with dynamic charge transfer between atoms where the interaction between atoms is described by the Es+ potential composed of the embedded atom method (EAM) potential and an electrostatic contribution. In the considered temperature range and under different gas pressure conditions, the growth kinetics follow a direct logarithmic law where the oxide thickness is limited to a value of ∼3 nm. The fitted curves allow us to determine the temperature and the pressure dependencies of the parameters involved in the growth law. During the adsorption stage, we observe a rotation of the oxygen pair as a precursor process to its dissociation. In most cases, the rotation aligns the molecule vertically to the Al surface. The separation distance after dissociation ranges from 3 to 9. Atomistic observations revealed that the oxide presents a dominant tetrahedral (Al O4) environment in the inner layer and mixed tetrahedral and octahedral (Al O6) environments in the outer oxide region when the oxide thickness reaches values beyond ∼2 nm.Conference Object Citation - WoS: 4Citation - Scopus: 6Robust Placement of Mobile Relational Operators for Large Scale Distributed Query Optimization(Institute of Electrical and Electronics Engineers Inc., 2007) Ergenç, Belgin; Morvan, Franck; Hameurlain, AbdelkaderThis paper presents a compile-time placement method of mobile relational operators MROs in a large scale environment. MROs are self adaptive to changing runtime conditions by deciding their execution place if they discover compile-time estimation errors. Proposed placement methods tend to have a main drawback with MROs running over a large scale environment: their focus is on finding optimal performance depending on single-point estimation at compile-time, instead of optimal performance over an estimation interval. We propose: (i) to determine the migration space of a MRO including the sites on which the MRO is allowed to migrate during its execution, and (ii) to find the robust site which will allow acceptable response time in an estimation interval. Performance study shows that, with a risk of loosing around 6% in response time, it is possible to gain up to 300% with the proposed robust placement.Article Citation - WoS: 41Citation - Scopus: 43Isomerisation of ?-Pinene Over Beta Zeolites Synthesised by Different Methods(Elsevier Ltd., 2005) Gündüz, Gönül; Dimitrova, Raina D.; Yılmaz, Selahattin; Dimitrov, Ljubomir; Spassova, MayaLiquid-phase α-pinene isomerisation at l00°C in a batch reactor is studied over Beta zeolites synthesised by different methods. It is confirmed that α-pinene forms a carbenium ion in an acidic environment, which rearranges without capture by nucleophiles, to form mainly hydrocarbons as camphene, terpinenes, terpinolenes and heavy products. The microporous Beta samples show low activity despite the high acidity most probably because of the hindered intermediate formation. The nature of the enhanced activity of Beta mesopores samples is suggested to be a result from the high accessibility of the acidic sites. The isomerisation of α-pinene was studied over Beta zeolites synthesised by different methods. The main products are camphene, terpinenes, terpinolenes and heavy products. Beta zeolites with micro-/mesopores reveal excellent activity because of the appropriate balance between acidity and bimodal pore system. The microporous Beta samples show low activity despite the good total acidity most probably because of the steric effect for the formation of the intermediate cations.