Focused ultrasound surgery (FUS) is considered as a promising approach for treating cancer and other conditions and is gaining increasing interest. However, the limited availability of experimental ultrasound array sources and multichannel electronics able to drive them hinder the research into FUS system configurations for patient conditions such as breast cancer. The work in this dissertation explored the development of ultrasound arrays for MRI guided FUS, from the point of view of the potential piezoelectric material of choice. Two materials are of particular interests in this work: Binary (x)Pb(Mg1/3Nb2/3) O3 - (1-x)PbTiO3 (PMN-PT) piezocrystal, and newly specialized FUS material, PZ54 ceramic. A characterization methodology was developed to fully characterize the materials of choice, under ambient and extreme conditions relevant to FUS applications. Practicalities of adopting these materials into FUS were studied by using the characterized materials in designing and fabricating FUS arrays. A spherical, faceted array geometry inspired by the geodesic dome structure was proposed and implemented for the first time. Four bespoke devices, each with 96 individual elements, were implemented using PZ26 ceramic, PZ26 composite, PZ54 composite and PMN-PT composite materials, respectively for comparison. The arrays were connected to commercial electronics afterwards, to explore a prototyping route for connecting FUS devices and modular driving systems. It is concluded that PMN-PT piezocrystal and PZ54 ceramic material can offer excellent performance over conventional piezoelectric ceramics, although PMN-PT piezocrystal is sensitive to extreme conditions. The usable range of PMN-PT is suggested to be limited to 60°C in temperature and 10 MPa in pressure. However, PMN-PT piezocrystal could still be a potential alternative to conventional ceramics in FUS application if assisted with sufficient cooling circulation and bias field. The geodesic array geometry is also concluded to be able to achieve good focusing of ultrasound beam. With optimized phase control through multi-channel electronics, the focusing was improved with focusing gain up to about 30; the steering range of focus was explored within a volume of 5 x 5 x 10 mm3 beyond the array’s geometric focus, side lobes were limited to below the level of -9 dB in acoustic intensity. Larger numbers of individual controllable elements and alternative array designs will be explored in future to investigate application such as breast cancer treatment and potential pre-clinical trials.

My dissertation focuses on (i) the development of new analysis tools and methodologies for analyzing X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) data, and (ii) the comprehensive characterization of materials (nanodiamonds) using a multi-instrument approach. Chapter 1 contains (i) a discussion of the two techniques I focused on most in my work: XPS and ToF-SIMS, (ii) a discussion of the common chemometrics techniques used to analyze data from these methods, and (iii) the advantages/rationale behind the multi-instrument characterization of materials. Chapter 2 describes various good practices for obtaining reasonable peak fits in XPS, which can also be applied to peak fitting data from different techniques. To address the issue of user subjectivity/bias in XPS peak fitting, I introduce two less biased mathematical functions for characterizing XPS narrow scans, namely the equivalent width (EW) and the autocorrelation width (AW). These functions are discussed in Chapters 3 and 4. In Chapter 5, I then introduce uniqueness plots as simple and straightforward graphical tools for assessing the quality of XPS peak fits and for determining whether fit parameters are correlated. This tool is extensively used in spectroscopic ellipsometry, and the mathematics behind it is known in XPS. However, to the best of my knowledge, this graphical tool has never been applied to XPS. ToF-SIMS data analysis is somewhat challenging due to the enormous amounts of data that are collected, and also the matrix effect in SIMS. This amount of information is significantly increased when depth profiles are performed on samples. Chapter 6 discusses a new chemometrics tool that I introduce for analysis of complex data sets, with emphasis on XPS and ToF-SIMS depth profiling data. The new approach is called the Information Content (IC) or entropy, which is adapted from Claude Shannon's work on Information Theory. Chapter 7 then contains a presentation of the comprehensive characterization of five nanodiamond samples used to manufacture particles for liquid chromatography. The advantages of a multi-instrument approach for material characterization and the lack of comprehensive material characterization in the literature are emphasized. To the best of my knowledge this is the most comprehensive characterization of nanodiamonds that has been reported in the literature. Chapter 8 presents conclusions of my work and future work. This thesis also contains six appendices. Appendix 1 contains an article from a scientific magazine that I wrote to highlight the importance and applications of the EW and AW to characterize XPS narrow scans. Appendices 2-5 are application notes I wrote on separations I performed on a nanodiamond based HPLC column. Finally, Appendix 6 describes the ToF-SIMS analysis of the tungsten species in the nanodiamond samples characterized in Chapter 7.

This thesis work deals with manufacturing a lightweight composite unmanned aerial vehicle (UAV) wing, material characterization of the composites used in the UAV wing, and preliminary structural analysis of the UAV wing. Manufacturing is performed at the composite laboratory founded in the Department of Aerospace Engineering, and with hand lay-up and vacuum bagging method at room temperature the wing is produced. This study encloses the detailed manufacturing process of the UAV wing from the mold manufacturing up to the final wing configuration supported with sketches and pictures. Structural analysis of the composite wing performed in this study is based on the material properties determined by coupon tests and micromechanics approaches. Contrary to the metallic materials, the actual material properties of composites are generally not available in the material handbooks, because the elastic properties of composite materials are dependent on the manufacturing process. In this study, the mechanical properties, i.e. Young&rsquo / s Modulus, are determined utilizing three different methods. Firstly, longitudinal tensile testing of the coupon specimens is performed to obtain the elastic properties. Secondly, mechanics of materials approach is used to determine the elastic properties. Additionally, an approximate method, that can be used in a preliminary study, is employed. The elastic properties determined by the tests and other approaches are compared to each other. One of the aims of this study is to establish an equivalent material model based on test and micromechanics approach, and use the equivalent model in the structural analysis by finite element method. To achieve this, composite structure of the wing is modeled in detail with full composite material descriptions of the surfaces of the wing structure, and comparisons are made with the results obtained by utilizing equivalent elastic constants. The analyses revealed that all three approaches have consistent, and close results / especially in terms of deflections and natural frequencies. Stress values obtained are also comparable as well. For a case study on level flight conditions, spanwise wing loading distribution is obtained using a program of ESDU, and the wing is analyzed with the distributed loading. Reasonable results are obtained, and the results compared with the tip loading case. Another issue dealt in this study is analyzing the front spar of the wing separately. The analysis of the front spar is performed using transformed section method and finite element analysis. In the results, it is found that both methods calculates the deflections very close to each other. Close stress results are found when solid elements are used in the finite element analysis, whereas, the results were deviating when shell elements are used in the analysis.

Lithium tetraborate (Li2B4O7) has aroused interest of scientists since 1960s by the courtesy of the thermoluminescence (TL) property it possesses. Over and above, it found widespread use in surface acoustic wave apparatuses, in sensor sector and in laser technology due to its non linear optical characteristics. For the uses in thermoluminescence dosimetry lithium tetraborate is activated by addition of a variety of metals as dopants. This study comprises the synthesis of lithium tetraborate by two methods (high temperature solid state synthesis and water/solution assisted synthesis) as well as doping and characterization of the material. Lithium tetraborate is readily commercially available in TL dosimetry / hence, the main aim is to specify practical production conditions to pioneer domestic production. In high temperature synthesis, the initial heating was performed at 400oC for 3 hours. Then the samples were heated at 750oC for two hours, intermittently mixed to enhance diffusion and exposed to the same temperature for another two hours. In water/solution assisted synthesis, stoichiometric quantities of reactants were mixed in water by heating and agitating in order to achieve homogenous mixing and good dispersion of the material. The remnant of water was removed from the system by 3 hours initial heating at 150oC. The synthesis stage is followed by doping step where the metals Cu, Ag and In in different proportions were doped in lithium tetraborate by solid state and solution assisted synthesis techniques. Powder X-ray diffraction method was employed for the characterization of the material. The thermal properties of doped and un-doped materials were studied by DTA (Differential Thermal Analyses). Besides, FT-IR (Fourier Transform Infra red) spectrometry analyses were performed in order to detect differences in the bond structure caused by doping The XRD patterns obtained showed that lithium tetraborate production was successful by both high temperature solid state synthesis and solution assisted synthesis Moreover, it was inferred from the XRD results that addition of dopants did not have a sound effect on the crystal structure. Furthermore, the DTA results displayed that addition of different dopants to the structure of lithium tetraborate did not cause any noticeable difference. The extensive TL measurements showed that the TL response of the material produced is affected by production and doping methods.

In this study, differences in glow curves of Mn doped LTB powder samples synthesized with solid and wet synthesis methods and doped by using solid and wet doping techniques were investigated. Firstly, LTB was synthesized by using wet synthesis method which mainly comprises dissolution of reactants in water as solvent. Second way to produce LTB which was used in this study was solid synthesis method. In solid synthesis method, reactants were mixed in powder form. In the second part of the study, LTB produced by two different methods were doped with Mn and additionally Ag, Mg or P by using two different doping techniques. In order to see structural differences between differently synthesized and differently doped LTB samples which contained different amount of dopant powder X-Ray Diffraction (XRD) method was employed. Besides, FTIR (Fourier Transform Infrared) spectroscopy analyses were performed in order to detect differences in the bond structure caused by doping. Additionally, Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) was used to determine the actual amount of dopant in LTB. Also morphological structures of samples were compared by using Scanning Electron Microscopy (SEM). Thermoluminescence measurements were performed with (TLD) Thermoluminescence Dosimeter equipment. XRD and FTIR analysis showed that syntheses of products were done in well success. Addition of dopants did not cause any changes in structural or bonding properties of LTB. It was possible to observe that, synthesis and doping methods and dopant concentration effect the thermoluminescence glow curves of doped LTB.

Strontium pyrophosphate is a promising phosphate that is used widely in the industry as a result of its luminescent, fluorescent, dielectric, semi-conductor, catalyst, magnetic and ion exchange properties. Thermoluminescent dosimetry (TLD) is one of such areas. Recent researches in METU on thermoluminescence property of strontium pyrophosphate showed that strontium pyrophosphate could give enough intensity for radiation dosimetry when doped with oxides of some rare-earth elements. In this study strontium pyrophosphate was synthesized and the product was doped with copper-silver, copper-indium and manganese-praseodymium ions by solid-state reaction. In addition to these processes, characterization and the investigation of thermoluminescence properties of strontium pyrophosphate with and without dopants was conducted. Stoichiometric quantities of strontium carbonate and ammonium dihydrogen phosphate were weighed, mixed and ground by agate mortar. Afterwards, the mixture was heated at 900&amp / #730 / C for 14.5 hours. For doping process, synthesized strontium pyrophosphate and different amounts of copper oxide, indium oxide, silver nitrate, manganese oxide and praseodymium oxide were weighed and powdered together. Then, mixture was heated at 950&amp / #730 / C for 11 hours. For characterization of strontium pyrophosphate samples with and without dopants / X-ray Diffraction (XRD) was implemented. Fourier Transform Infrared Spectroscopy (FTIR) was used to determine whether the bond structures were affected from doping or not. Thermal properties of the samples were investigated with the help of Differential Thermal Analysis (DTA). Morphology of compounds was observed by Scanning Electron Microscope (SEM). Afterwards thermoluminescence (TLD) studies were carried out. XRD pattern of samples showed that the intensity of hkl-310 peak of strontium pyrophosphate increased with the inclusion of metal oxides, however none of the characteristic peaks of metal oxides was observed. Addition of metal oxides caused no change in FTIR meaning that the anionic part of matrix compound, which is strontium pyrophosphate, has structural stability. Thermal analysis and morphological investigation of this material were performed. TLD results were different for each sample, which has different content. The most significant peak, which is suitable for radiation dosimetry was observed at 160&amp / #730 / C in the glow curve with the sample doped with 7% manganese oxide and 1% praseodymium oxide.

A novel material characterization method for magneto-dielectric composite material was proposed. MD materials have been reported as providing new opportunities for effective antenna size reduction in many studies. Since MD materials have to be realized through material synthesis, an accurate measurement method is required to extract them. The proposed method, cavity perturbation technique using substrate integrated waveguide cavity resonator, has been demonstrated through theories, simulations and measurement that it can be used to extract both electric and magnetic properties of the MD composite material effectively. MD materials using cobalt-fluoropolymer have been synthesized and material design guidelines for antenna applications are also provided. The benefits of using MD materials on antenna miniaturization was also demonstrated by comparing the performance of an antenna on MD material to other antennae on high dielectric constant materials and FR-4 material. Through simulations and measurements, the MD material is a promising solution for next generation smartphone or wearable type applications.

Low temperature cracking is a major distress in asphalt pavements. Several test configurations have been introduced to characterize the fracture properties of hot mix (HMA); however, most are considered to be research tools due to the complexity of the test methods or equipment. This dissertation describes the development of the indirect ring tension (IRT) fracture test for HMA, which was designed to be an effective and user-friendly test that could be deployed at the Department of Transportation level. The primary advantages of this innovative and yet practical test include: relatively large fracture surface test zone, simplicity of the specimen geometry, widespread availability of the required test equipment, and ability to test laboratory compacted specimens as well as field cores. Numerical modeling was utilized to calibrate the stress intensity factor formula of the IRT fracture test for various specimen dimensions. The results of this extensive analysis were encapsulated in a single equation. To develop the test procedure, a laboratory study was conducted to determine the optimal test parameters for HMA material. An experimental plan was then developed to evaluate the capability of the test in capturing the variations in the mix properties, asphalt pavement density, asphalt material aging, and test temperature. Five plant-produced HMA mixtures were used in this extensive study, and the results revealed that the IRT fracture test is highly repeatable, and capable of capturing the variations in the fracture properties of HMA. Furthermore, an analytical model was developed based on the viscoelastic properties of HMA to estimate the maximum allowable crack size for the pavements in the experimental study. This analysis indicated that the low-temperature cracking potential of the asphalt mixtures is highly sensitive to the fracture toughness and brittleness of the HMA material. Additionally, the IRT fracture test data seemed to correlate well with the data from the distress survey which was conducted on the pavements after five years of service. The maximum allowable crack size analysis revealed that a significant improvement could be realized in terms of the pavements performance if the HMA were to be compacted to a higher density. Finally, the IRT fracture test data were compared to the results of the disk-shaped compact [DC(t)] test. The results of the two tests showed a strong correlation; however, the IRT test seemed to be more repeatable.

Bolts and rivets are produced by cold forging technique. A great majority of metal forming companies prefer to use their dexterity rather than science and technology. The main aim of this thesis is to establish an environment for developing technology in bolt production by reducing trial and error. In this thesis finite element method is utilized to model bolt forming for correcting tooling designs, removing production defects and estimating forging forces. Material characterization, precise determination of boundary conditions and verification of numerical results are also investigated. It is shown how efficient the finite element method is for technology development in metal forming industry. Furthermore, two anomalies in extrusion process are presented: The hump and the force hill in extrusion force-displacement curve. Reasons of these two anomalies are studied using finite element simulations and verified by experiments. Thesis also explains reduction methods of three-dimensional problems to axisymmetric models and compares the results.

Cemented carbide containing sub carbide phases, M6C and M12C, known as eta-phase, increases the lifetime milling cutters due to increased resistance to comb cracks. When milling, the inserts much sustain high temperatures, meaning edgeline toughness and thermal fatigue resistance are needed. To obtain this, finer grains and higher binder content are needed. In this study, WC-Co cemented carbides with eta-phase and Cr as well as a higher binder content are investigated. The microstructure is the focus, with parameters such as eta-phase particle size and volume fraction, WC grain size being evaluated. Another part of the study is the investigate the effect of Cr on heat treatment. The addition of Cr in a WC-Co cemented carbide with eta-phase has shown to give rise to smaller eta-phase particle sizes and WC grain size as compared to without Cr. Also, increasing the volume fraction of eta-phase has less influence on WC and eta-phase particle size. Heat treated samples without Cr is shown to increase the coercivity of the samples at 700 degrees Celsius, without change in WC grain size. The effect is also leading to an increase in hardness. But with addition of Cr, the effect seems to diminish.