ABSTRACT EXCHANGES OF STRONTIUM ON CLINOPTILOLITE ZEOLITE G&Uuml / L, &Ouml / zkan MS, Department of Chemical Engineering Supervisor: Prof. Dr. Hayrettin Y&uuml / cel November 2003, 110 Pages Sr-90 and Cs-137, nuclear fission products, are the major sources of medium-level radioactive waste which must be decontaminated. Inorganic ion exchangers are the preferred materials to eliminate radioisotopes from aqueous nuclear waste because of their high selectivity, radiation and thermal stability, low cost and likely compatibility with cement containment. Clinoptilolite and other zeolites are widely used in nuclear industry for the removal of radioisotopes from aqueous nuclear waste. In this study, the performance of local clinoptilolite zeolite from G&ouml / rdes region has been investigated so as to determine the conditions under which it can be used effectively in the column for strontium and cesium removal. It was found that under different loading conditions, breakthrough capacity varied from 0 to 0.4078 meq/g for strontium removal, breakthrough capacity varied from 0.1178 to 0.7800 meq/g for cesium removal. It was also determined that the increase of the flow rate reduced the exchange capacity of the bed. Effect of cationic form of the zeolite (Na-CLI: Sodium form of clinoptilolite and Original-CLI: Original form of clinoptilolite) on the breakthrough capacity was also searched. It was observed that Na-CLI performed much better for the removal of strontium and cesium with respect to its original form. In addition, effect of presence of calcium in the feed solution on the breakthrough capacity was investigated and it was found that presence of calcium in the feed solution makes strontium removal essentially impossible, in the case of cesium, presence of calcium in the feed solution decreases breakthrough capacity significantly.

ABSTRACT ENCAPSULATION OF WHEAT GERM OIL Yazicioglu, Basak M.Sc., Department of Food Engineering Supervisor: Prof. Dr. Serpil Sahin Co- Supervisor: Prof. Dr. G&uuml / l&uuml / m Sumnu February 2013, 82 pages Wheat germ oil is a rich source of omega 3 and omega 6, octacosanol and tocopherol which has vitamin E activity. Due to these properties it is beneficial for health but it is prone to oxidation in free form. The aim of this study was to encapsulate wheat germ oil in micron size and determine the best encapsulation conditions by analysing encapsulation efficiency, particle size distribution and surface morphology of the capsules. The effects of core to coating ratio, coating materials ratio and ultrasonication time on encapsulation of wheat germ oil were investigated. Maltodextrin (MD) and whey protein concentrate (WPC) at different ratios (3:1, 2:2, 1:3) were used as coating materials. Total solid content of all samples was 40% (w/w). Five different core to coating ratios (1:8, 1:4, 2:4, 3:4, 4:4) were experimented. Ultrasound was used at 320 W and 20 kHz frequency for three different times (2, 5, 10 min). Prepared emulsions were frozen and then freeze dried for 48 hours to obtain microcapsules. Encapsulation efficiency analysis, particle size analysis and scanning electron microscopy (SEM) analysis were performed. Increasing WPC content in coating led to an increase in encapsulation efficiency. Microcapsules prepared with MD:WPC ratio of 1:3 were found to have higher encapsulation efficiencies (65.62%-89.62%) than the other ratios. Increase in oil load led to decrease in encapsulation efficiency thus 1:8 core to coating ratio gave better results. The best conditions for microcapsules were determined as ultrasonication time 10 min, core to coating ratio of 1:8 and MD:WPC ratio 1:3.

Shack-Hartmann wavefront sensors are commonly used in optical alignment, ophthalmology, astronomy, adaptive optics and commercial optical testing. Wavefront error measurement yields Zernike polynomials which provide useful data for alignment correction calculations. In this thesis a practical alignment method of a helmet visor is proposed based on the wavefront error measurements. The optical system is modeled in Zemax software in order to collect the Zernike polynomial data necessary to relate the error measurements to the positioning of the visor. An artificial neural network based computer program is designed and trained with the data obtained from Zernike simulation in Zemax software and then the program is able to find how to invert the misalignments in the system. The performance of this alignment correction method is compared with the optical test setup measurements.

Geographically located materials are used by the archaeology to analyze and explain the socio-cultural aspects of ancient life. Thus, Geographical Information Systems (GIS) have started to be used in archaeology for many applications. Although, cooperation of GIS and archaeology is considered as beneficial, it has become insufficient to meet the requirements of archaeologists about excavation study. Therefore, the aim of this thesis is to develop Spatial Decision Support System (SDSS) which includes both the GIS tools and analyses and / analytical modeling capabilities in order to satisfy the needs of archaeologists. Moreover, to develop a specialized system for specific archaeological excavation site is aimed. In this study, Kaunos is selected as a case study area and in order to furnish this aim, firstly, needs of archaeologists working in the excavation study of Kaunos are analyzed. Secondly, GIS tools and analyses are determined which meet the requirements of archaeologists. Finally, SDSS for Kaunos Archaeological Excavation Site is developed. It is composed of four components namely / Database Management, Model Management, Dialog Management and Stakeholder Components. Analyses are conducted under the Model Management Component and results are visualized in Dialog Management Component. Result maps help and assist archaeologists in terms of interpreting and examining the socio-cultural, economical and demographical characteristics of Kaunos.

In this thesis, the pulse diversity technique in radar systems in high clutter environments is investigated. In this technique, different pulse compression methods are used in each pulse in the transmitted burst to increase the unambiguous range. In pulse diversity, the design of filters used in the receiver is as important as designing the transmitted waveform. At the output of pulse-burst filter that processes pulse-by-pulse, as many channels as the pulses in the burst occur. Each of these channels is matched to a certain range interval. In order to improve the detector performance, the phase codes used in the transmitted pulse-burst waveform and their corresponding filters must have good auto-correlation and cross-correlation properties, either individually or as their sum. In the literature some phase codes, having mentioned properties, are present. However, the performance of these codes in radar applications is not fully evaluated. The studies in the thesis show that the codes in the literature cannot be used directly in radar applications. In the scope of thesis, optimization criteria suitable for radar applications are defined and applied according to the mentioned requirements. Then, the obtained phase codes are tested in the radar simulator and the obtained results of the simulations are evaluated.

This thesis presents the formation mechanism of intermetallics formed at Fe-Al film interfaces. Al thin films with different initial film thicknesses were coated on low carbon steel substrates by physical vapor deposition (PVD). By annealing the system at different temperatures and for different time intervals, several intermetallic phases were observed. X-Ray, SEM and EDS studies showed that intermetallic phases FeAl2 and Fe2Al5 are most dominant phases which were observed and they formed sequentially on the contrary of intermetallics which formed synchronous in bulk materials.

The objective of this study is to determine the mean heat transfer coefficient and heat transfer rate and to analyse the effect of inclination angles,the effect of subcooling temperatures and the effect of vapour velocity for laminar filmwise condensation of water vapour on a vertical tier of spheres experimentaly and analyticaly. For this purpose, the experimental aparatus were designed and manufactured. In the free condensation experimental study &Oslash / 50mm and &Oslash / 60 mm O.D. spheres were used to analyse the diameter effect . In the experimental studies of free and forced condensation &Oslash / 60mm O.D. spheres on which vapour flows at 2,75 bars were used to analyse the effect of vapour velocity. For the experimental study of the annular condensation in the concentric spheres the effect of vapour velocity was studied by forcing the vapour to flow in the area between two concentric spheres. In the free condensation experiments it is observed that at smaller diameters the heat flux and mean heat transfer coefficients for sphere is higher. In the free and forced condensation experiments increasing the velocity of vapour increases the mean heat transfer coefficient. At the experiments with annular condensation between the concentric spheres high mean heat transfer coefficient values have been obtained compared to the free and forced condansation over the surface of spheres experimental studies.

The swell waves which are an important component of wind generated waves have significant effects on small craft and fisheries. The swell wave climate has an important role in the design and operation of fishing harbors and harbors for small craft. Despite this fact the swell wave climate is not well known for the Turkish coasts. The purpose of the present study was to identify the swell wave climate along the Black Sea coastline of T&uuml / rkiye. For this purpose wind and swell wave data for a 65 months period is obtained from ECMWF for the analysis. And the data are analyzed for thirteen locations selected along the Turkish coast. For every location the wind and swell wave roses, significant swell wave height versus Mean period of primary swell relations, extreme probability distribution and log-linear cumulative probability distribution are presented. Also some extreme swell events in the Black Sea occurred in the data period are presented for a better understanding of generation and propagation of swell waves. The results showed that the swell wave activity and severity is higher in the western Black Sea coastline of T&uuml / rkiye. The investigation of extreme swell events provided that the swell waves occur and diminish in a relatively short duration and the data available from ECMWF which is provided for 12 hour intervals is not sensitive to time enough for the investigation of swell wave occurrence and propagation. The significant swell wave height versus Mean period of primary swell relations and analysis on period of swell waves showed that the swell wave periods could reach up to 11 seconds in the Northern shores of T&uuml / rkiye.

The various versions of CreditRisk+ have widely been used in the financial industry. We compute the loss distribution under CreditRisk+ model by fast fourier transform technique in order to have faster and more stable results. Moreover, we link the parameters of the model to the exogenously observed variables which could be obtained from the financial markets by the use of Poisson INAR process. It is shown that the estimation of the parameters become available under this setup. This enables us to build a system that allows users to monitor and predict the banks loss characteristics without having specific and current information on banks.

In this study, effect of cold stress and recovery on the superoxide dismutase (SOD) activities and the expression levels of Cu/ZnSOD gene were investigated in two barley cultivars (Tarm-92-winter type, Zafer-160-spring type). Eight days old barley seedlings were subjected to two different cold stresses / chilling stress at 4&deg / C for 1, 3, 7 days and freezing stress at -3&deg / C and -7&deg / C. Analyses were performed both on leaf and root tissues. The SOD activities and isozyme patterns were determined by Native PAGE activity staining technique. Relative RT-PCR was used for the transcript levels of Cu/ZnSOD gene. The SOD activities and expression levels of control and cold stressed plants were compared by densitometric analysis. Under chilling stress, the activities of Cu/ZnSODx and Cu/ZnSOD2 did not have any significant change in leaf and root tissues of both cultivars. However, the expression levels of Cu/ZnSOD gene were more variable than activity results. After -3&deg / C freezing stress, the activities of SOD enzyme in leaf tissues of Tarm-92 increased significantly, however, these activities significantly decreased in leaves of Zafer-160. These results suggested that both cultivars were not affected by chilling stress in terms of SOD enzyme activities and expression levels. Furthermore, under freezing stress conditions, the increment of SOD activities and expression levels in Zafer-160 was higher than Tarm-92. In conclusion, the changes in SOD isozyme activities and expression levels may not be enough for understanding of the cold stress mechanism. Therefore, further studies have to be carried on other antioxidant enzyme systems.