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In this dissertation, we examine mechanics of rhythmic tracheal compression (RTC) in the darkling beetle, Zophobas morio. In Chapter 2, we studied the relationship between hemolymph pressure and tracheal collapse to test the hypothesis that pressure is a driving mechanism for RTC. We found that tracheae collapse as pressure increases, but other physiological factors in the body may be affecting tracheal compression in live beetles. Additionally, as the tracheae compress, they do so in varying spatial patterns across the insect body. In chapter 3, we examined spatial variations in the taenidial spacing, stiffness, and tracheal thickness along the length of the tracheae. We related variations in Young's modulus and taenidial spacing with measurements of collapse dimples and found that spatial patterns of Young's modulus correlate with dimensions of collapse dimples. This correlation suggests an intuitive link between tracheal stiffness variations and the unique patterns observed in compressing tracheae. Lastly, in chapter 4, we studied the non-uniform collapse patterns in 3-D. By manually pressurizing the hemocoel and imaging using synchrotron microcomputed tomography (SR-µCT), we reconstructed the tracheal system in its compressed state. While previous studies used 2-D x-ray images to examine collapse morphology, ours is the first to quantify collapse patterns in 3-D and compare with previous 2-D quantification methods. Our method is also the first to make a direct measure of tracheal volume as the tracheal system compresses, similar to the phenomenon that occurs during rhythmic tracheal compression. / Doctor of Philosophy / Insects have long been a source of curiosity and inspiration for scientists and engineers. The insect respiratory system stands as an example of a seemingly complex oxygen delivery system that operates with relative simplicity. As opposed to mammals and other vertebrates, the insect respiratory system does not deliver oxygen using blood. Instead, insects possess a massive network of hollow tracheal tubes that are distributed throughout the body. Air enters spiracular valves along the length of the insect body, travels through the tracheal tube network, and is delivered directly to the tissues. In some insects, the tracheae compress and expand, driving flow of respiratory gasses. However, unlike vertebrate lungs, there are no muscles directly associated with the tracheal system that would drive this tracheal compression, and exactly how this behavior occurs is not fully understood. In this dissertation, we examined pulsatory increases in blood pressure as a possible mechanism that underlies these tracheal compressions in the darkling beetle, Zophobas morio. Additionally, as the tracheae compress, they do so with varying spatial patterns across the insect body. Because tracheae are complex and non-uniform composite tubes, we examined spatial variations in the microstructure, stiffness, and tracheal thickness along the length of the trachea. Lastly, we visualized the variable collapse patterns in three dimensions using synchrotron micro-computed tomography combined with manual pressurization of the hemocoel. While previous studies used two-dimensional x-ray images to quantify tracheal collapse patterns, this work represents the first three-dimensional study. Understanding tracheal collapse mechanics, material properties, and their relationships with the circulatory system can help to gain an understanding of how insects create complex fluid flows within the body using relatively simple mechanisms.

With increasing frequency up to the THz frequency range and the desire to optimize performance of modern applications, precise knowledge of the dielectric material parameters of a substrate being used in a planar application is crucial: High performance of the desired device or circuit can often be achieved only by properly designing it, using specific values for the material properties. Especially the integration of planar devices for very broadband applications at high frequencies often demands specific dielectric properties such as a low permittivity, dispersion and loss, assuring a predictable performance over a broad frequency range. Therefore, material characterization at these frequencies is of interest to the developing THz community, although not a lot of methods suitable in terms of frequency range and measurement setup exist yet. In this work, a comprehensive method for dielectric material parameter determination from S-Parameter measurements of unloaded and loaded planar transmission lines up to THz frequencies is developed. A measurement setup and methodology based on wafer prober measurements is established, which allows for characterization of planar substrates and bulk material samples alike. In comparison with most existing methods, no specialized measurement cell or cumbersome micro-machining of material samples is necessary. The required theory is developed, including a discussion of effective parameter extraction methods from measurement, identification of and correction for undesired transmission line effects such as higher order modes, internal inductance and surface roughness, as well as mapping and modelling procedures based on physical permittivity models and electromagnetic simulations. Due to the general approach and modular structure of the developed method, new models to cover additional aspects or enhance its performance even further are easily implementable. Measurement results from 100 MHz to 500 GHz for planar substrates and from 100 MHz to 220 GHz for bulk material samples emphasize the general applicability of the developed method. It is inherently broadband, while the upper frequency limit is only subject to the fabrication capabilities of modern planar technology (i.e. minimum planar dimensions of transmission lines and height of substrate) and thus is easily extendable to higher frequencies. Furthermore, the developed method is not bound to a specific measurement setup and applicable with other measurement setups as well, as is exemplary presented for a free-space setup using antennas, enabling measurement of large, flat material samples not fitting on the wafer prober. Several substrate and bulk material samples covering a wide range of permittivities and material classes are characterized and compared with reference values from literature and own comparison measurements. The uncertainties for both planar substrate as well as bulk material sample measurements are estimated with a single-digit percentage. For all measurements, the order of magnitude of the dielectric loss tangent can be determined, while the lower resolution boundary for bulk material sample measurements is estimated to 0.01. Concerning measurements in the wafer prober environment, fixture-related issues are a main cause of measurement uncertainty. This topic is discussed as well as the design of on-wafer probe pads and custom calibration standards required for broadband operation at THz frequencies. / Mit zunehmender Erschließung des THz-Frequenzbereichs und der zugehörigen Optimierung moderner Anwendungen ist eine genaue Kenntnis der dielektrischen Materialparameter verwendeter planarer Substrate unabdingbar: Eine hohe Performance angestrebter Bauteile oder Schaltungen kann nur durch einen präzisen Entwurf sichergestellt werden, wofür spezifische Werte für die Materialeigenschaften bekannt sein müssen. Insbesondere die Integration planarer Bauelemente für sehr breitbandige Anwendungen bei hohen Frequenzen bedingt spezifische dielektrische Materialeigenschaften, wie bspw. geringe Permittivität, Dispersion und Verluste, sodass eine vorhersagbare Performance über einen breiten Frequenzbereich sichergestellt werden kann. Materialcharakterisierung bei diesen Frequenzen ist folglich von Interesse für die sich entwickelnde THz-Forschungslandschaft, wenngleich derzeit kaum Verfahren existieren, die geeignet in Bezug auf den Frequenzbereich oder Messaufbau sind. Im Rahmen dieser Arbeit wird ein umfassendes Verfahren zur Bestimmung der dielektrischen Materialparameter aus S-Parameter-Messungen unbelasteter und belasteter planarer Leitungen bis in den THz-Bereich entwickelt. Ein Messaufbau mitsamt Messmethodik basierend auf Wafer Prober-Messungen wird entworfen, welcher die Charakterisierung von planaren Substraten und losen Materialproben ermöglicht. Im Vergleich zu existierenden Verfahren ist weder eine spezielle Messzelle noch eine umständliche Mikrobearbeitung der Materialproben notwendig. Die Entwicklung der hierfür notwendigen Theorie beinhaltet eine Diskussion von Methoden zur Extraktion effektiver Parameter aus Messungen, die Identifikation und Korrektur unerwünschter Leitungseffekte wie bspw. höherer Moden, interner Induktivität und Oberflächenrauhigkeit sowie Zuordnungs- und Modellierungsverfahren basierend auf physikalischen Permittivitätsmodellen und elektromagnetischen Simulationen. Durch den allgemeinen, modularen Ansatz des entwickelten Verfahrens lassen sich neue Modelle zur Berücksichtigung zusätzlicher Effekte oder weiteren Verbesserung der Performance einfach einarbeiten. Messergebnisse von 100 MHz bis 500 GHz für planare Substrate und von 100 MHz bis 220 GHz für lose Materialproben unterstreichen die allgemeine Anwendbarkeit des entwickelten Verfahrens. Es ist inhärent breitbandig, wobei eine obere Frequenzgrenze nur durch die Fertigungstoleranzen moderner planarer Technologien gegeben ist (minimale Leitungsdimensionen und Substrathöhe), sodass es einfach zu höheren Frequenzen hin erweiterbar ist. Weiterhin ist das entwickelte Verfahren nicht an einen bestimmten Messaufbau gebunden und auch mit weiteren Aufbauten anwendbar, wie beispielhaft an einem Freiraum-Aufbau mit Antennen präsentiert wird. Eine Vielzahl planarer Substrate und loser Materialproben, die ein weites Spektrum an Permittivitäten und Materialklassen abdecken, werden charakterisiert und mit Referenzdaten aus der Literatur sowie eigenen Messungen verglichen. Die Messunsicherheiten der Permittivitätsmessungen werden im einstelligen Prozentbereich abgeschätzt und der dielektrische Verlustwinkel kann in seiner Größenordnung bestimmt werden. Aufbaubezogene Einflüsse als eine Hauptursache für Messunsicherheiten am Wafer Prober werden adressiert, ebenso wie der Entwurf von On-Wafer Probe Pads und selbsterstellter Kalibrierstandards, die notwendig sind für den Einsatz bei THz-Frequenzen.

There is a need to monitor the existence and effects of damage in structural materials. Aircraft components provide a much publicized example, but the need exists in a variety of other structures, such as layered materials used in food packaging industries. While several techniques and models have been proposed for material characterization and condition monitoring of bulk materials, less attention has been devoted to thin sheets having no flexural rigidity. This study is therefore devoted to the development of a new method for acoustic Non-Destructive Testing (NDT) and material characterization of thin sheets used in food packaging materials or similar structures. A method for assessing the strength in the presence of crack of thin sheets used in food packaging is first presented using a modified Strip Yield Model (SYM). Resonance frequency measurement is then introduced and it is shown, at low frequency range (less than 2kHz), that a change in the physical properties such as a reduction in stiffness resulting from the onset of cracks or loosening of a connection causes detectable changes in the modal properties, specifically the resonance frequency. This observation leads to the implementation of a simple method for damage severity assessment on sheet materials, supported by a new theory illustrating the feasibility of the detection of inhomogeneity in form of added mass, as well as damage severity assessment, using a measurement of the frequency shift. A relationship is then established between the resonance frequency and the material’s elastic property, which yields a new modality for sheet materials remote characterization. The result of this study is the groundwork of a low-frequency vibration-based method with remote acoustic excitation and laser detection, for nondestructive testing and material characterization of sheet materials. The work also enhances the feasibility of the testing and condition monitoring of real structures in their operating environment, rather than laboratory tests of representative structures. The sensitivity of the new experimental approach used is liable to improvement while being high because the frequency measurement is one of the most accurate measurements in physics and metrology.

The development of modern digital communication systems has been entered a new era with faster signal transmission and processing capability, called high-speed circuit systems. As their clock frequencies have increased and rise times of signals have decreased, the signal integrity of interconnects in the packaging and printed circuit boards plays a more and more important role. In high-speed circuit systems, the well-designed logic functions most likely will not work well if their interconnects are not taken into account.This dissertation addresses to profoundly understand the signal integrity knowledge, be proficient in calculation, simulation and measurements, and be capable of solving related signal integrity problems. The research mainly emphasizes on three aspects. First of all, the impact of on-wafer calibration methods on the measured results of coplanar waveguide circuits is comprehensively investigated, with their measurement repeatability and accuracy. Furthermore, a method is presented to characterize the physically-consistent broadband material properties for both rigid and flexible dielectric materials. Last but not least, a hybrid method for efficient modeling of three dimensional via structures is developed, in order to simplify the traditional 3D full-length via simulations and dramatically reduce the via build and simulation time and complexity.

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.