In this study, effect of cold stress on physiology and biochemistry of two Turkish barley cultivars, winter type Tarm-92 and spring type Zafer-160, was studied. For chilling stress treatment, cultivars were exposed to +4 &ordm / C for 1, 3 and 7 days, and for freezing stress application acclimated cultivars (+4 &ordm / C for 3 days) were treated with -3 &ordm / C and -7 &ordm / C. After freezing stress treatment, a recovery period was applied for 4 days at 4 &ordm / C. Following analyses were performed on leaf and root tissues: growth parameters (length, wet-dry weights), malondialdehyde (MDA) content, proline content, hydrogen peroxide content (H2O2) electrolyte leakage, PS II fluorescence (Fv/Fm), antioxidant enzyme activities such as catalase (CAT: EC 1.11.1.6), ascorbate peroxidase (APX: EC 1.11.1.11) and glutathione reductase (GR: EC 1.6.4.2). It was observed that effect of cold was more at freezing temperatures than chilling temperature. Cold dependent damage was more obvious as the duration of chilling temperature increased. Growth retardation, membrane damage, leaf catalase deactivation were more apparent and leaf glutathione reductase activity increase was less in spring type cultivar Zafer than in winter type Tarm. These results indicated that winter type barley cultivar is more cold tolerant than spring type barley.

In this study, inventory&ndash / routing system of a company operating in Fast Moving Consumer Goods (FMCG) industry is analyzed. The company has decided to redesign distribution system by locating regional warehouses between production plants and customers. The warehouses in the system are all allowed to hold stock without any capacity restriction. The customers are replenished by the warehouse to which they have been assigned. Customer stocks are continuously monitored by the warehouse and deliveries are to be scheduled. In this multi&ndash / item, two-echelon inventory&ndash / distribution system, main problem is synchronizing inventory and distribution decisions. An integrated Mixed Integer Programming optimization model for inventory and distribution planning is proposed with the aim of optimally coordinating inventory management and vehicle routing. The model determines the replenishment periods of items and amount of delivery to each customer / and constructs the delivery routes with the objective of cost minimization. The integrated model is coded in GAMS and solved by CPLEX. The integrated inventory-routing model is simulated with retrospective data of the company. Computational results on test problems are provided to show the effectiveness of the model developed in terms of the performance measures defined. Moreover, the feasible solution obtained for a period is compared to the realized inventory levels and distribution schedules. Computational results seem to indicate a substantial advantage of the integrated inventory-routing system over the existing distribution system.

Metamodeling is a very popular approach for the approximation of complex systems. Metamodeling techniques can be categorized according to the type of regression method employed as linear and nonlinear models. The Response Surface Methodology (RSM) is an example of linear regression. In classical RSM metamodels, parameters are estimated using the Least Squares (LS) Method. Robust regression techniques, such as Least Absolute Deviation (LAD) and M-regression, are also considered in this study due to the outliers existing in data sets. Artificial Neural Networks (ANN) and Multivariate Adaptive Regression Splines (MARS) are examples for non-linear regression technique. In this thesis these two nonlinear metamodeling techniques are constructed and their performances are compared with the performances of linear models.

A great interest in 3-D modeling in Geographic Information Technologies (GIS) has emerged in recent years, because many GIS related implementations, ranging from urban area design to environmental analysis require 3-D models. Especially the need for 3-D models is quite urgent in urban areas. However, numerous applications in GIS only represent two-dimensional information. The GIS community has been struggling with solving complex problems dealing with 3-D objects using a 2-D approach. This research focused on finding most accurate method which is used for getting height information that is used in 3D modeling of man made structures in urban areas. The first method is estimating height information from floor numbers of the buildings data from municipal database systems. The second method is deriving heights of buildings from Digital Elevation Model (DEM) that is generated from stereo satellite images. The third method is measuring height values of the buildings from 3D view of stereo IKONOS satellite images by operators. The comparisons between these three methods are done with respect to height data collected from field study, and according to these comparisons, the amount of the error is determined. The error is classified according to floor numbers of buildings, so that, the quantified errors can be applied for similar works in future. Lastly, the third method is utilized by the assistance of 10 people who have different experience level about 3D viewing, in order to see the error amount changes according to different operators. Several results are presented with a discussion of evaluation of the methods applied. It is found that, if there is an updated floor number database, obtaining building height is the most accurate way from this database. The second most accurate method is found to be getting height information by using 3D view of stereo IKONOS images through experienced users.

Factors such as economical development, rapid increase in population and climate change increased electricity demand in Turkey as well as in other countries. Thus, using the correct methods to estimate short, medium and long term electricity demand forms a basis for the countries to develop their energy strategy. In this study, monthly electricity demand of Turkey is estimated. First, the effect of natural gas price and consumption to electricity demand and elasticities are searched with a simple regression model. Although, natural gas is known as a substitute of electricity, natural gas consumption and natural gas over electricity price ratio are found to be nearly inelastic. Second part includes two models and cointegration relation is investigated in nonstationary industry production index, electricity consumption per capita and electricity prices series in the first one. An error correction model is then formed with an additional average temperature variable and 12 months electricity demand is forecasted. In the second one, heating degree-days and cooling degree-days are used instead of the average temperature variable and a new error correction model is formed. The first model performs better than the second one, indicating the seasonality of electricity consumption during a year. The results of both models are also compared with previous studies to investigate the effect of different weather variables.

In the first part of the study, birchwood xylan-lignin film formation was studied. After film forming effect of lignin on pure birchwood xylan was demonstrated, the minimum lignin concentration necessary to form films was determined as 1.1% (lignin/xylan). So, it was determined that keeping about one percent lignin in xylan (w/w) was sufficient for film formation. Biodegradability of the lignin-birchwood xylan composite films was investigated enzymatically using 0.21 U / ml xylanase in an accelerated test. All the films containing lignin were hydrolyzed by xylanase showing biodegradability of the films. Colors of the birchwood xylan-lignin composite films containing different lignin concentrations were compared. Deviations of the color from the reference color were similar between the films. In the second part of the study, photocatalytic antimicrobial film production was investigated on wheat gluten-based films. In order to produce antimicrobial films, wheat gluten films were coated with a semiconductor, titanium dioxide (TiO2), applying different procedures. Coated films were illuminated and photocatalytical inactivation of Escherichia coli on films were determined by antimicrobial tests. The coating procedure in which titanium dioxide (TiO2) was produced from titanium tetraisopropoxide (TTIP) in aqueous-nitric acid and aqueous-hydrochloric acid solutions gave the best antimicrobial result but the films turned out to be deformed and brittle. Spreading TiO2 sol-gel on semi-dried wheat gluten films resulted in flexible and undeformed films having about 40% antimicrobial activity.

The further developments in nanotechnology in last few years provide usage of nanoscale particles for many applications in various areas such as electronics, pharmaceutical, and biomedical due to their strengthened mechanical, thermal and electrical properties. Boron nitride nanotubes are a good example of nanoparticles. In this study, boron nitride nanotubes were successfully synthesized from the reaction of ammonia gas with mixture of boron and iron oxide. Physical and structural properties of the synthesized materials were determined by X-Ray Diffraction, Energy Dispersive X-Ray Spectroscopy, nitrogen sorption, X-Ray Photoelectron Spectroscopy, Fourier Transform Infrared Spectroscopy, and Scanning Electron Microscopy. Experiments were conducted in a tubular furnace at different temperatures and also at different weight ratios of boron to iron oxide. Qualitative chemical analysis of the reactor effluent stream was carried out using a mass spectrometer. The mass spectrometer analysis of the reaction products proved formation of nitrogen in addition to hydrogen and water during the reaction of ammonia gas with the mixture of boron and iron oxide. XRD results showed that hexagonal and rhombohedral boron nitrides and cubic iron were the solid phases formed in the product. FTIR and XPS results also indicated the presence of boron nitride and the atomic ratio of boron to nitrogen was compatible with the chemical stoichiometric relation between boron and nitrogen. It was observed that the crystanility of the product increased with an increase in temperature. The diameter of the produced nanotubes varied from 64 nm to 136 nm. The synthesized nanotubes exhibited Type II isotherms. The surface areas of the produced boron nitride nanotubes decreased with a decrease in both temperature and the weight ratio of boron to iron oxide. The best temperature and weight ratio of boron to iron oxide to produce boron nitride nanotubes were found to be 1300&deg / C and 20, respectively.

The aim of this thesis work was to develop magnetoelectric (ME) composites consisting of piezoelectric and magnetostrictive components. The piezoelectric constituent was selected as a PZT ceramic modified by strontium, bismuth and manganese. The magnetostrictive phase was nickel ferrite (NF) ceramic doped by cobalt, copper and manganese. The properties of component phases were optimized in order to enhance the ME effect in the composite. In the first part of the thesis, effects of sintering temperature on the dielectric and piezoelectric properties of PZT and on the electrical and magnetic properties of NF ceramics were investigated in the temperature range covered from 1150 to 1250 &deg / C. The best piezoelectric properties in PZT were attained at 1250 &deg / C. At this sintering temperature, values of piezoelectric strain coefficient, dielectric constant, and electromechanical coupling coefficient were 434 pC/N, 1320 and 0.48, respectively. NF ceramics showed poor densification / 80 %TD was attained at 1250 &deg / C. In order to obtain higher densities in ferrites, Bi2O3 was used as a sintering aid. Addition of Bi2O3 enhanced densification up to 97 %TD, and improved electrical and magnetic properties of ferrites. Highest DC-resistivity of 1.15*10^8 ohm-cm and highest magnetostriction of ~26 ppm were attained in NF ceramics doped with 1 wt% Bi2O3. In the second part of the thesis, ME composites were manufactured either as bulk composites or as laminated composites. The efficiency of different composite types was evaluated in terms of voltage output in response to the applied magnetic field. Higher outputs were observed in laminated composites.

A candidate hydrogen storing material should have high storage capacity and fast dehydrogenation kinetics. On this basis, magnesium hydride (MgH2) is an outstanding compound with 7.66 wt % storage capacity, despite its slow dehydriding kinetics and high desorption temperature. Therefore in this study, bulk and surface alloys of Mg with improved hydrogen desorption characteristics were investigated. In this respect, formation energies of alloyed bulk MgH2 as well as the adsorption energies on alloyed magnesium (Mg) and MgH2 surface structures were calculated by total energy pseudopotential methods. Furthermore, the effect of substitutionally placed dopants on the dissociation of hydrogen molecule (H2) at the surface of Mg was studied via Molecular Dynamics (MD). The results displayed that 31 out of 32 selected dopants contributed to the decrease in formation energy of MgH2 within a range of ~ 37 kJ/mol-H2 where only Sr did not exhibit any such effect. The most favorable elements in this respect came out to be / P, K, Tl, Si, Sn, Ag, Pb, Au, Na, v Mo, Ge and In. Afterwards, a systematical study within adsorption characteristics of hydrogen on alloyed Mg surfaces (via dynamic calculations) as well as calculations regarding adsorption energies of the impurity elements were performed. Accordingly, Mo and Ni yielded lower adsorption energies / -9.2626 and -5.2995 eV for substitutionally alloyed surfaces, respectively. MD simulations presented that Co is found to have a splitting effect on H2 in 50 fs, where the first hydrogen atom is immediately adsorbed on Mg substrate. Finally, charge density distributions were realized to verify the distinguished effects of most 3d and 4d transition metals in terms of their catalyzer effects.

In this study, the first hardfill dam in Turkey, Cindere Dam, is evaluated regarding current and alternative measurement systems in detail. Cindere Dam is a notable project, especially with its height as an example of hardfill dam, not only in Turkey but also in the world. First, the current instrumentation system of Cindere Dam is evaluated as a whole with reference to the parameters measured, instruments and data acquisition system. Second, an alternative instrumentation system is developed by using additional parameter and instruments to the current instrumentation system. Furthermore, each instrumentation system equipped with manual and automatic data acquisition systems is considered. The comparison between the current and the alternative instrumentation systems are also carried out in terms of technical and economical feasibility aspects. Although, the current instrumentation system is found to be satisfactory, it is observed that the alternative system promotes the current system in various aspects without increasing the cost significantly.