In this thesis study, a new method for finding the optimum geometries of atomic nanoparticles has been developed by modifying the well known diffusion Monte Carlo method which is used for electronic structure calculations of quantum mechanical systems. This method has been applied to homonuclear and heteronuclear atomic clusters with the aim of both testing the method and studying various properties of atomic clusters such as radial distribution of atoms and coordination numbers. Obtained results have been compared with the results obtained by other methods such as classical Monte Carlo and molecular dynamics. It has been realized that this new method usually finds local minima when it is applied alone and some techniques to escape from local minima on the potential energy surface have been developed. It has been concluded that these techniques of escaping from local minima are key factors in the global optimization procedure.

In the development of engineering products, it is necessary to predict dynamic properties of the modified structures. Achieving such predictions by using the structural properties of the original structure and information on the modifications is commonly referred to as structural modification analysis. In this thesis, &Ouml / zg&uuml / ven&rsquo / s Structural Modification Method and Sherman-Morrison Method are selected as exact methods for structural modifications to predict the dynamics of a locally modified structure. Also, a new structural modification method named as &ldquo / Extended Successive Matrix Inversion Method&rdquo / is developed in this study. These three methods are implemented in a software developed herein, called &ldquo / Structural Modification Toolbox&rdquo / . The software uses modal analysis results of MSC Nastran&copy / for the original structure and calculates the modified frequency response functions by any of the methods above. In order to validate the software, direct modal analysis results of MSC Nastran&copy / for the frequency response functions of the modified structure are used. The methods are compared in terms of computational time, and the effectivity of each method is studied as a function of modification size to determine which of these methods is more suitable. In order to investigate the application of the methods and compare their results with experimental ones, modal tests are conducted on a scaled aircraft structure. The solutions are compared with test results obtained from modified test structure. Additionally, the software is used for comparison of real aircraft test results and frequency response functions of the modified structure.

The analytical and numerical modeling of CO2 sequestration in deep saline aquifers having different properties was studied with diffusion and convection mechanisms. The complete dissolution of CO2 in the aquifer by diffusion took thousands, even millions of years. In diffusion dominated system, an aquifer with 100 m thickness saturated with CO2 after 10,000,000 years. It was much earlier in convective dominant system. In diffusion process, the dissolution of CO2 in aquifer increased with porosity increase / however, in convection dominant process dissolution of CO2 in aquifer decreased with porosity increase. The increase in permeability accelerated the dissolution of CO2 in aquifer significantly, which was due to increasing velocity. The dissolution process in the aquifer realized faster for the aquifers with lower dispersivity. The results of convective dominant mechanism in aquifers with 1md and 10 md permeability values were so close to that of diffusion dominated system. For the aquifer having permeability higher than 10 md, the convection mechanism began to dominate gradually and it became fully convection dominated system for 50 md and higher permeability values. These results were also verified with calculated Rayleigh number and mixing zone lengths. The mixing zone length increased with increase in porosity and time in diffusion dominated system. However, the mixing zone length decreased with increase in porosity and it increased with increase in dispersivity and permeability higher than 10 md in convection dominated system.

Gait analysis is one of the primary applications of biomechanics and deals with scientific description of human locomotion, which is a qualitative concept as observed through the human eye. METU Gait Analysis Laboratory has been operating in various fields of gait and motion analyses since 1999. Although several studies have previously been undertaken about METU Gait Analysis System, until now, the effects of methodology and protocol related system parameters on kinematic analysis results have not been fully and exhaustively investigated. This thesis presents an assessment on sensitivity and compatibility of METU Gait Analysis Protocol to variations in experimental methodology and implementation of various joint center estimation methods, performed through investigation of the resulting joint kinematics. It is believed that the performance and reliability of METU Gait Analysis System will be improved based on the findings of this study.

The METU Gait Analysis System employs a computer program called Kiss-GAIT for the calculation of joint angles, moments and powers using force plate data and marker trajectories as input. Kiss-GAIT was developed using Delphi and is confined to calculations related to the standard gait protocol. Because the code lacks the flexibility required to carry out various test cases, the inverse dynamics formulation being used could not be verified and the extent of the error propagation problem could not be determined so far. The first aim of this study was to develop a code for the inverse dynamics model of the METU Gait Analysis System making use of the flexible programming environment provided by MATLAB. Verified and more reliable analysis results, obtained by reformulating the inverse dynamics algorithm in a new code, are presented. Secondly, data smoothing and differentiation techniques conventionally used in gait analysis were critically reviewed. A common tool used for filtering marker trajectories is the Butterworth digital filter. This thesis presents a modified, adaptive version of this classical tool that can handle non-stationary signals owing to its coefficients which are functions of local signal structure. The results of this thesis indicate the dominancy of ground reactions as compared to inertial effects in normal human gait. This implies that the accuracy needed in body segment inertial parameter estimation is not a critical factor. On the other hand, marker trajectories must be as accurate as possible for meaningful kinetic patterns. While any smoothing and differentiation routine that produces reasonable estimates is sufficient for joint moment calculation purposes, the estimation performance becomes a key requirement for the calculation of joint powers.

In recent decades, tremendous efforts have been made to obtain high hydrogen storage capacity in a stable configuration. In the literature there are plenty of experimental works investigating different materials for hydrogen storage and their storage values. In the first part of this thesis the available literature data have been collected and tabulated. In addition to the literature survey the hydrogen storage capacity of carbon nanotubes and carbon nanotubes doped with boron nitride (CBN nanotubes) with different chirality have been investigated by performing quantum chemical methods at semiempirical and DFT levels of calculations. It has been found that boron nitrite doping increases the hydrogen storage capacity of carbon nanotubes. Single wall carbon nanotubes (SWNT) can be thought as formed by warping a single graphitic layer into a cylindrical object. SWNTs attract much attention because they have unique electronic properties, very strong structure and high elastic moduli. The systems under study include the structures C(4,4), H2@C(4,4), C(7,0), C(4,0), and the BN doped C(4,4), H2@C(4,4), 2H2@C(4,4), C(7,0), H2@C(7,0), 2H2@C(7,0). Also, we have investigated adsorption and desorption of hydrogen molecules on BN doped coronene models by means of theoretical calculations.

The main aim of the thesis is to analyse the recent socio-spatial patterns of Istanbul, in which squatter areas on publicly-owned land (gecekondu) and old historical centre of the city are subjected to regeneration projects, under the impact of making Istanbul a purified place for the significant social classes via exclusion of the others. The formulations of Henri Lefebvre for analysing the production of (social) space are used as the conceptual framework of the thesis. To reveal the case study, the recent urban regeneration projects in Istanbul, a wide range of qualitative data collection techniques and methodology, documentary analysis, in-depth interviews, participant observations, which will pave a way to understand the complex relations among social and spatial formations, are used. According to the analysis on the acceleration of urban regeneration projects in the city of Istanbul, the thesis argues two main points: Firstly, the specificity of urbanisation period in Istanbul after 2000 is characterised with the strong role of the central state, mainly MHA. Secondly, the people, who are living in the gecekondu areas and old historical centres in the inner city are not only evicted from their living spaces, they are also socially and spatially excluded from the city centres.

With the emergence of urban transformation concept in 1980s, the concept of eligibility has also started to be discussed as a new term in Turkey. However, the absence of a sustainable urban transformation law which defines the criteria of eligibility of stakeholders has undoubtedly brought about violations and disagreements between stakeholders. Especially the uncertified gecekondu possessors who are not determined as eligible stakeholders have been subjected to forced and arbitrary evictions. This study aims to clarify the problem of eligibility of uncertified gecekondu possessors in urban transformation and attempts to determine the criteria for the eligibility of this particular group. It argues that since the claims of uncertified gecekondu possessors like right to adequate housing, labor and possession have moral characters which do not depend upon legal acts, they can not be criteria of eligibility. The legal property ownership must be the criteria of eligibility in urban transformation practices in the law. On the other hand, this study urges that no matter living in a legal or illegal housing, the vulnerable families who lack of basic economic security and living in the project area must be determined as eligible stakeholders. In the first part of this master study, the problem of eligibility was discussed from theoretical perspective. In the second part, this problem was discussed in the case of Dikmen Valley 4th and 5th phases Urban Transformation Project. The knowledge obtained from the case can be useful for the local governments to develop sustainable policies on this particular problem.

In this study, silicon (Si) rich silicon dioxide (SiO2) films and terbium (Tb) embedded in three different Si containing films has been produced by e-beam evaporation and magnetron sputtering techniques. Post deposition annealing was done for different temperatures and durations to study its effect on both Si nanocrystal formation and Tb luminescence. It was verified by X-ray diffraction technique (XRD) that Si nanocrystals were formed in Si rich matrices. Energy dispersive X-ray (EDS) spectroscopy analysis was carried out to determine the relative concentrations of the atoms inside the produced films. X-ray photoelectron spectroscopy (XPS) gave the evidence of different bonding structures inside the Tb-Si-O containing films. Depth profile measurements were carried out to analyze changes in the relative concentration during sputtering of the layers after annealing of the Tb containing film. Luminescence characteristics of Si nanocrystals and Tb3+ ions were studied by photoluminescence (PL) spectroscopy. It was observed that Tb3+ luminescence enhanced by an energy transfer from Si nanocrystals and trap levels in a matrix. This result supplies valuable information about the excitation paths of Tb3+ ion the way of intense luminescence.

The main subject of this thesis is the investigation of the transformations of pure multipartite entangled states having Schmidt rank 2 by using only local operations assisted with classical communications (LOCC). A new parameterization is used for describing the entangled state of p particles distributed to p distant, spatially separated persons. Product, bipartite and truly multipartite states are identified in this new parametrization. Moreover, alternative parameterizations of local operations carried out by each party are provided. For the case of a deterministic transformation to a truly multipartite final state, one can find an analytic expression that determines whether such a transformation is possible. In this case, a chain of measurements by each party for carrying out the transformation is found. It can also be seen that, under deterministic LOCC transformations, there are some quantities that remain invariant. For the purpose of applying the results of this thesis in the context of the quantum information and computation, brief reviews of the entanglement purification, measurement based quantum computation and quantum codes are given.