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Development Of A Software For Determination Of Kinetic Parameters In Thermal AnalysisErtunc, Goker 01 September 2011 (has links) (PDF)
In this thesis, a new software, THERA-Kinetics was developed for the evaluation of kinetic parameters using non-isothermal data. Different computational methods, available in the software, were applied to a set of experimental and simulated data distributed in the ICTAC (International Confederation for Thermal Analysis and Calorimetry) Kinetics Project. The reliability of the software was verified by comparing the kinetic results, which were in good agreement, with those obtained by the participants of the ICTAC Kinetics Project.
It was also within the scope of this study to examine the combustion characteristics and kinetics of three same origin coal samples. A series of thermogravimetry (TG) and differential scanning calorimetry (DSC) measurements were carried out in non-isothermal conditions at heating rates of 5, 10 and 15 K/min. Reaction regions, peak and burn-out temperatures, weight loss percentages and heat of reactions of the samples were determined for each heating rate from TG and DSC curves. A variety of computational methods, available in the software developed, were applied to experimental data for the evaluation of the kinetic parameters of the coal samples. It was observed that there was no general trend in the activation energy values from the point of heating rate.
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Phase Transformation And Magnetic Properties Of Multicomponent Heusler Type AlloysKalkanci, Mine 01 September 2011 (has links) (PDF)
Many Co-based Heusler alloys with the stoichometric composition X2YZ are ideal candidates for the spintronics applications. So, they have been extensively studied theoretically and experimentally. The aim of this work was to investigate the effect heat treatment on phase stability and magnetic properties for quaternary Co2FeSi1-xGax Heusler alloys with varying Si concentration. The Co2FeSi1-xGax alloy samples were prepared by conventional arc melting technique. The structure of Co2FeSi1-xGax bulk alloys were examined by powder x-ray diffraction and differential scanning calorimetry. It was confirmed that Co2FeSi1-xGax alloys display the L21 type structure for all x compositions based on the annealing temperature. The magnetic ordering transition temperature, Tc, was measured by differential scanning calorimetry. It was found that the order-disorder phase transition temperature from the L21 to the B2 structure, T , decreases while the Curie temperature, Tc, increases with increasing x / however, the value of these temperatures were not influenced by changing heat treatment process. The magnetic properties of Co2FeSi1-xGax alloy were investigated by using vibrating sample magnetometer. Higher saturation value was obtained at the L21 phase than the value obtained at the B2 phase. It was concluded that the Co2FeSi0.2Ga0.8 alloy was chosen optimum composition for spintronics applications because of its highest Curie temperature and phase stability of L21.
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Photofermentative Hydrogen Production Using Dark Fermentation Effluent Of Sugar Beet Thick Juice By Rhodobacter CapsulatusOzkan, Endam 01 September 2011 (has links) (PDF)
Biological hydrogen production through integration of dark and photo-fermentation by using biomass is a promising alternative for energy supply problems. The main purpose of this study was to investigate photobiological H2 production by the purple non-sulfur (PNS) bacteria Rb. capsulatus on dark fermentation effluent of sugar beet thick juice (DFESBTJ). Presence of NH4+ in effluents is an important parameter since NH4+ inhibit the nitrogenase enzyme activity. Therefore, the influence of different NH4+ concentrations in the DFESBTJ by removing using natural zeolite clinoptilolite on photofermentative H2 production were studied using Rb. capsulatus DSM1710 and Rb. capsulatus YO3 (hup-). Also, the effect of EtOH concentrations (between 6.25 and 200 mM) in the defined medium on H2 production were studied using both bacterial strains since EtOH is a possible by-product of dark fermentation process. The experiments were carried out in small scale bottle photobioreactors (PBRs) and outdoor panel PBR (4 L). H2 productivity of 1.12 mmol/Lc/h was
attained over 15 days of operation for panel PBR. The results showed that the zeolite was effective in removing NH4+ from the DFESBTJ as its concentration decreased by 95% after treatment. In both bacterial strains, an increase in the maximum
productivities and molar H2 yields was observed with the decrease in NH4+concentrations. There was no significant effect of EtOH on H2 production except the inhibition at 200 mM. The main conclusions were that both bacterial strains could
effectively utilize the DFESBTJ for growth and H2 production, therefore facilitating the integration of the dark and photo-fermentation for sustainable biohydrogen production.
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In Vitro Selection Of Dna Aptamers To Glioblastoma MultiformeBayrac, Abdullah Tahir 01 September 2011 (has links) (PDF)
Aptamer probes for specific recognition of glioblastoma multiforme were generated using a repetitive and broad cell-SELEX-based procedure without negative selection. The 454 sequencing technology was used to monitor SELEX, and
bioinformatics tools were used to identify aptamers from high throughput data. A group of aptamers were generated that can bind to target cells specifically with dissociation constants (K d ) in the nanomolar range. Selected aptamers showed high affinity to different types of glioblastoma cell lines, while showing little or no affinity to other cancer cell lines. The aptamers generated in this study have
potential use in different applications, such as probes for diagnosis and devices for targeted drug delivery, as well as tools for molecular marker discovery for glioblastomas.
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Comparison Of Sub-processes And Final Products Of Iron And Steel Production With Life Cycle AssessmentOlmez, Gulnur 01 December 2011 (has links) (PDF)
Iron and steel production is one of the most resource and energy demanding industries around the world. Throughout the life cycle of iron and steel products, the intensive use of raw materials and energy results in contributions to a wide range of environmental impacts. This study conducts a life cycle assessment (LCA) for iron and steel production in Turkey using SimaPro software and IMPACT 2002+ impact assessment method with the purpose of comparing the impacts of life cycle stage (coke making, sintering, iron making, steel making) and final products (billet, slab, hot rolled wire rod, hot rolled coil). The system boundary was set as cradle-to-gate, the functional unit was selected as 1 ton of product, and the study was conducted using the inventory data collected from one of the three integrated iron and steel facilities representing the majority of the industry in Turkey. Different production scenarios for the final products were also evaluated to see the variation in the total impacts. The results indicated that, liquid steel production process exhibited the highest total environmental impact, which was followed by sinter production. Coke production process showed the highest impact on depletion of non-renewable energy sources. The comparison of the impacts for different final products revealed that hot rolled coil causes the highest total environmental impact. Moreover, the environmental impact of mechanical workshop of the facility was found negligible when compared to the production processes.
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Cruise Missile Mission RehearsalBircan, Gokhan 01 December 2011 (has links) (PDF)
Cruise missile mission planning is a key activity of cruise missile operations. Ground planning activities aim at low observable missions that have high probability of success. These activities include end game planning, route planning and launch planning. While end game planning tries to optimize end game parameters for maximum effectiveness, route planning tries to maximize survivability and enable navigational supports by determining the waypoints to from launch zone to target through a defended area. And lastly, planner tries to find the appropriate launch parameters that will prohibit platform to contact enemy agents. Mission rehearsal is the execution of the planned mission in a virtual environment that will be constructed with the data that drives the planning process. Mission rehearsal will support planners by providing possible results of the planned mission. Stochastic processes of the execution of the planned mission will be incorporated in the simulation of the combat. Along with platform, cruise missile and target, other players like SAM Sites or Search Radars (Early Warning Radars) will be incorporated in the rehearsal process.
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An Adaptive Unscented Kalman Filter For Tightly-coupled Ins/gps IntegrationAkca, Tamer 01 February 2012 (has links) (PDF)
In order to overcome the various disadvantages of standalone INS and GPS, these systems are integrated using nonlinear estimation techniques and benefits of the two complementary systems are obtained at the same time. The standard and most widely used estimation algorithm in the INS/GPS integrated systems is Extended Kalman Filter (EKF). Linearization step involved in the EKF algorithm can lead to second order errors in the mean and covariance of the state estimate. Another nonlinear estimator, Unscented Kalman Filter (UKF) approaches this problem by carefully selecting deterministic sigma points from the Gaussian distribution and propagating these points through the nonlinear function itself leading third order errors for any nonlinearity. Scaled Unscented Transformation (SUT) is one of the sigma point selection methods which gives the opportunity to adjust the spread of sigma points and control the higher order errors by some design parameters. Determination of these parameters is problem specific. In this thesis, effects of the SUT parameters on integrated navigation solution are investigated and an &ldquo / Adaptive UKF&rdquo / is designed for a tightly-coupled INS/GPS integrated system. Besides adapting process and
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measurement noises, SUT parameters are adaptively tuned. A realistic fighter flight trajectory is used to simulate IMU and GPS data within Monte Carlo analysis. Results of the proposed method are compared with standard EKF and UKF integration. It is observed that the adaptive scheme used in the sigma point selection improves the performance of the integrated navigation system especially at the end of GPS outage periods.
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Experimental Characterization Of Some Water Soluble Polymers Used In Drilling And Completion FluidsGurbuz, Berkay 01 February 2012 (has links) (PDF)
Properly preparing the drilling fluid is an essential part of any successful drilling operation, especially in complex operations like deviated and horizontal drilling. Understanding the flow behavior of the polymers used in the drilling fluids under different conditions takes a key part in this preparation. In this study, shear rheology of some traditionally used water soluble polymers in drilling and completion fluids / namely PAC (polyanionic cellulose) and xanthan gum, were investigated experimentally. Instead of an oilfield standard Fann Model 35 Viscometer, an Ofite Model 900 Viscometer was used because of its capability to measure at ultra-low shear rates. Effects of the concentration of the polymer, time of shear applied, test temperature and effects of aging were examined. Rheological
measurements were conducted between the shear rate ranges of 0.01 to 1000s-1 with concentrations changing from 0.25 to 1.5 grams of polymer per 350 milliliters of water (equivalent to 0.25 to 1.5 lb/bbl). Rheograms were constructed to identify the effect the polymers in question have on the flow characteristics of the drilling fluid. An appropriate constitutive
model was used to define the flow behavior of the polymer in question mathematically.
It was observed from the constructed rheograms that increase in polymer concentration results in consistent increase of apparent viscosity. Amount of time of shear does not affect the selected polymers if they are dynamically aged at least for two hours. Also as expected increasing temperature of the sample lowers the apparent viscosity considerably.
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Development Of Pozzolanic Lime Mortars For The Repair Of Historic MasonryGuney, Bilge Alp 01 February 2012 (has links) (PDF)
The use of lime mortars with pozzolanic additives is of special importance for the repair of historic masonry. In this study, the effect of pozzolanic materials on the final characteristics of mortars was investigated. Metakaolin, fly ash and historic brick powder were used as pozzolanic materials in mortar mixes with varying binder:pozzolan:aggregate ratios. Historic mortar samples from rubble stone masonry of Kahta Castle, a medieval structure in close vicinity of the Nemrut Dag Monument, were also investigated to serve as a starting point for the preparation of repair mortars. Physical and physicomechanical tests, optical microscopy, chemical tests, SEM-EDX and XRD analyses were used to assess the properties of the historic mortars and repair mortars.
Fat lime was found to be used in historic mortars with a high binder/aggregate ratio. They were observed to have relatively low density and high porosity with an average compressive strength of 7.4 MPa. Historic mortars were determined to have relatively high water vapour permeability and low water impermeability characteristics.
In repair mortars setting was found to be predominantly due to carbonation along with pozzolanic reactions. However, abundant presence of stratlingite in mortars with added metakaolin indicated that the pozzolanic reactions preceded carbonation in those mortars.
Use of pozzolanic materials increased the uniaxial compressive strength and modulus of elasticity of mortars compared with control samples. Using the same binder:pozzolan:aggregate ratio, highest increase was observed on mortars prepared with added fly ash at the end of 90 days. Durability parameters of repair mortars defined as wet to dry compressive strength were in the very good to excellent range according to Winkler&rsquo / s classification. By using fly ash, design of lime mortars with high water impermeability and high water vapour permeability characteristics was accomplished.
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Location Analysis Of The Mobile/24 Emergency Service Vehicles Of A Case CompanyYetkin, Raife Meltem 01 June 2012 (has links) (PDF)
The aim of this study is planning the locations of emergency centers (ECs) as well as the number of vehicles in each EC of Corporation, Man Truck and Bus Group, to respond to the calls (arrival of the mobile/24 emergency service vehicle to the broken vehicle) within the desired time. The company aims to respondto the calls within 90 minutes. If the EC cannot respond to the calls within 90 minutes, they should be satisfiedwithin 180 minutes. We propose a probabilistic programming approach to maximize the number of responded calls in 90 minutes while responding to all the calls in 180 minutes. The model determines the locations of the new ECs addition to the existing ones and also the number of vehicles assigned to those centers. The data source to this study is the emergency service calls of the company within February 2008 and December 2010. There are 30 ECs of the company distributed all over Turkey. By using the data, it is examined if the company can get closer to its target in responding to the calls with the current ECs. Necessary changes are proposed in the number and the locations of emergency centers for the desired target. Furthermore, several scenarios for targets with different quality service levels are generated and the effects of these parameters on the objective are observed.
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