A self-sensing material can not only carry a load but can also provide data aboutthe load and stress it’s being subjected to. Traditional additive manufacturing haslimited capabilities in producing self-sensing material. Existing 3D printers eitherused in industry or in scientific applications are either limited by closed-off software and planar motion which limits the design freedom, or the type of material orcost often limiting the attainability. Being capable of placing self-sensing materialwith full design freedom means that the sensor structure as well as the load carryingpart of the material can be tailored to the application specific use of the material,making application specific load carrying and sensing capabilities possible. Themanufacturing method produced in this aims to solve these existing limitations. Aliterature review in the topic of additive manufacturing of self-sensing material andcontinuous Carbon Fiber Reinforced Thermoplastics (CFRTPs) has been producedas a literature base. The review seeks to educate and inspire the design of an noveladditive manufacturing method and device capable of printing a self-sensing material as well as non-planar motion. A design for extruding self-sensing material andnon-planar motion has been realized through modified Commercial-Off-The-Shelf(COTS) parts and Geometric Code (G-Code). Existing hardware capable of producing this can be priced in the range of 70 000 C, but this result has been achievedwith around 200 C [42]. A software structure capable of manufacturing the selfsensing material has been produced. Real-world testing in terms of extrusion of theself-sensing material and non-planar motion has been tested and proven which arethe main practical outcomes demonstrating the technological feasibility.

[pt] Nesta dissertação nós discutimos as técnicas de modelos de matrizes para gravidade quântica em duas dimensões, as triangulações dinâmicas (DT) e sua versão causal, chamada de triangulações dinâmicas causais (CDT). Em virtude do teorema de Gauss-Bonnet a ação de Einstein-Hilbert se torna um invariante topológico em duas dimensões, por conseguinte, a avaliação da integral de caminho se transforma em um simples problema combinatório de contagem dos diagramas desenhados em uma superfície de Riemann, o que implica numa expansão topológica da função de partição. Usando métodos de integrais da teoria quântica de campos, podemos entender a correspondência entre modelos de matrizes e a formulação em grade da gravidade quântica, onde as N × N matrizes Hermitianas geram gráficos planares. Uma vez que a integral matricial se reduz a uma integração dos seus autovalores, solucionamos o modelo matricial utilizando duas técnicas: polinômios ortogonais e a análise do ponto de sela. Usando os polinômios ortogonais calculamos a energia livre no limite planar para diferentes potenciais. Por fim, partindo dos modelos matriciais estudamos DT e CDT numa analogia com o gás de Coulomb. / [en] In this thesis we discuss the matrix models techniques applied to two dimensional quantum gravity, the dynamical triangulations (DT) approach and its causal version, so-called causal dynamical triangulations (CDT). By virtue of the Gauss-Bonnet theorem, the Einstein-Hilbert action in two dimensions becomes a topological invariant, thereupon the evaluation of the path integral becomes a simple combinatorial counting problem of graphs drawn on a Riemann surface, which leads to a topological expansion of the partition function. Using integral methods from quantum field theory we can understand the correspondence between large N matrix models and a lattice (DT and CDT) formulation of quantum gravity, where the N ×N Hermitian matrices generates planar graphs (fatgraphs). Once the matrix integral is reduced to an integral of its eigenvalues, we solve the matrix model using two techniques: Orthogonal polynomials and saddle point analysis. Using orthogonal polynomials we compute the free energy in the Large N limit for different potentials. Finally, we study DT and CDT using matrix models and further make contact with a Coulomb gas analogy.

<p>This work presents the development and/or application of several laser diagnostics for studying the flame structure of composite propellant flames. These studies include examining the flame structure of novel energetic materials with potential as propellant ingredients, the near-surface flame structure of basic composite propellants, and the global flame structure of propellants containing metal additives.<br></p><p><br></p><p>First, the characterization of the deflagration of various novel energetic cocrystals is presented. The synthesis and development of novel energetic materials is a costly and challenging process. Rather than synthesizing new materials, cocrystallization provides the potential opportunity to achieve improved properties of existing energetic materials. This work presents the characterization of the effect of cocrystallization on the deflagration of a 2:1 molar cocrystal of CL-20 and HMX as well as a 1:1 molar cocrystal of CL-20 and TNT. A hydrogen peroxide (HP) solvate of CL-20 as well as a polycrystalline composite of HMX and ammonium perchlorate (AP) were also studied. A physical mixture of each material was also tested for comparison. The burning rate of each material was measured as a function of pressure. Flame structure during self-deflagration was examined using planar laser-induced fluorescence (PLIF) of CN and OH. The burning rate of the HMX/CL-20 cocrystal and the CL-20/HP solvate closely matched that of CL-20, but the burning rate of the TNT/CL-20 cocrystal was between the burning rate of its coformers. All HMX/AP materials had a higher burning rate than either HMX or AP individually and the burning rate of a physical mixture was found to be a function of particle size. The differences in the burning rate of the physical mixtures and composite crystal of HMX/AP can be explained by changes in the flame structure observed using PLIF. Burning rates and flame structure of the cocrystals were found to closely match those of their respective physical mixtures when smaller particle sizes were used (approx. less than 100 um). The results obtained demonstrate that the deflagration behavior of the coformers is not indicative of the deflagration behavior of the resulting physical mixture or cocrystal. However, changes in the resulting flame structure greatly affect the burning rate.</p><p><br></p><p>Next, PLIF of nitric oxide (NO) was utilized to characterize the near surface flame structure of composite propellants of AP and hydroxyl-terminated polybutadiene (HTPB) containing varying particle sizes of AP burning at 1 atm in air. In all propellants, the NO PLIF signal was strongest close to the burning propellant surface and fell to a non-zero constant value within ~1 mm of the surface where it remained throughout the remainder of the flame. Distinct diffusion-flame-like structure was observed above large individual burning AP particles in the propellant containing a bimodal distribution of 400 and 40 um AP. In contrast, the flame of a propellant containing only fine AP (40 um) behaved like a homogeneous, premixed flame. The flame of the propellant containing a bimodal distribution of 200 and 40 um AP also showed similar behavior to a premixed flame with some heterogeneous structure indicating that, at this pressure, the propellant is approaching a limit where the particle sizing is small enough that the flame behaves like a homogeneous, premixed flame. Additionally, propellants containing aluminum were tested. No significant differences were observed in the NO PLIF behavior between the propellants with and without aluminum suggesting that, at these conditions, the aluminum does not have a significant effect on the AP/HTPB flame structure near the burning surface.</p><p><br></p><p>The effect of aluminum particle size on the temperature of aluminized-composite-propellant flames burning at 1 atm is also presented. In this work, measurements of 1) the temperature of CO (within the flame bath gas) and 2) the temperature of AlO (located primarily within regions surrounding the burning aluminum particles) within aluminized, AP-HTPB-propellant flames were performed as a function of height above the burning propellant surface. Three aluminized propellants with varying aluminum particle size (nominally 31 um, 4.5 um, or 80 nm) and one non-aluminized AP-HTPB propellant were studied while burning in air at 1 atm. A wavelength-modulation-spectroscopy (WMS) diagnostic was utilized to measure temperature and mole fraction of CO via mid-infrared wavelengths and a conventional AlO emission-spectroscopy technique was utilized to measure the temperature of AlO. The bath-gas temperature varied significantly between propellants, particularly within 2 cm of the burning surface. The propellant with the smallest particles (nano-scale aluminum) had the highest average temperatures and far less variation with measurement location. At all measurement locations, the average bath-gas temperature increased as the initial particle size of aluminum in the propellant decreased, likely due to increased aluminum combustion. The results support arguments that larger aluminum particles can act as a heat sink near the propellant surface and require more time and space to ignite and burn completely. On a time-averaged basis, the temperatures measured from AlO and CO agreed within uncertainty at near 2650 K in the nano-aluminum propellant flame, however, AlO temperatures often exceeded CO temperatures by ~250 to 800 K in the micron-aluminum propellant flames. This result suggests that in the flames studied here, and on a time-averaged basis, the micron-aluminum particles burn in the diffusion-controlled combustion regime, whereas the nano-aluminum particles burn within or very close to the kinetically controlled combustion regime.</p><p><br></p><p>The study of the effect of aluminum particle size on the temperature of aluminized, composite-propellant flames was then extended to characterize the same propellants burning at elevated pressures ranging from 1 to 10 atm. A novel mid-infrared scanned-wavelength direct absorption technique was developed to acquire measurements of temperature and CO in particle-laden propellant flames burning at up to 10 atm. The results from the application of this diagnostic are among the very first measurements of gas properties in aluminized composite propellant flames burning at pressures above atmospheric pressure. In all propellants, the flame temperature and combustion efficiency of the propellant flames increased with an increase in pressure. In addition, the propellants with smaller aluminum particle sizes achieved higher flame temperatures as the particles were able to ignite and react faster. However, the propellants containing nano-scale and the smallest micron-scale aluminum powders had similar global flame temperatures suggesting that at some point a decrease in particle size results in minimal gains in the overall flame temperature. The results demonstrate how well measurements of gas properties can be used to understand the behavior of the aluminum particle combustion in the flame.</p><p><br></p><p>Last, the design, development, and application of a laser-absorption-spectroscopy diagnostic capable of providing quantitative, time-resolved measurements of gas temperature and HCl concentration in flames of aluminized, composite propellant flames is presented. This diagnostic utilizes a quantum-well distributed-feedback tunable diode laser emitting near 3.27 um to measure the absorbance spectra of one or two adjacent HCl lines using a scanned-WMS technique which is insensitive to non-absorbing transmission losses caused by metal particulates in the flame. This diagnostic was applied to characterize the spatial and temporal evolution of temperature and/or HCl mole fraction in small-scale flames of AP-HTPB composite propellants containing either an aluminum-lithium alloy or micron-scale aluminum. Experiments were conducted at 1 and 10 atm. At both pressures, the flame temperature of the aluminum-lithium propellant, on a time-averaged basis, was 80 to 200 K higher than that of the aluminum-propellant (depending on location in the flame) indicating more complete combustion. In addition, the mole fraction of HCl in the aluminum-lithium propellant flame reached values 65-70% lower than the conventional aluminum-propellant flame at the highest measurement location in the flame. The measurements at both pressures showed similar trends in the reduction of HCl in the aluminum-lithium propellant flame but at 10 atm this occurred on a length scale an order of magnitude smaller than the flame at atmospheric pressure. The results presented further support that the use of an aluminum-lithium alloy is effective at reducing HCl produced by the propellant flame without compromising performance, thereby making it an attractive additive for solid rocket propellants.</p>

Solid Oxide Fuel Cells are fuel cells that operate at high temperatures usually in the range of 600oC to 1000oC and employ solid ceramics as the electrolyte. In Solid Oxide Fuel Cells oxygen ions (O2- ) are the ionic charge carriers. Solid Oxide Fuel Cells are known for their higher electrical efficiency of about 50-60% [1] compared to other types of fuel cells and are considered very suitable in stationary power generation applications. It is very important to study the effects of different parameters on the performance of Solid Oxide Fuel Cells and for this purpose the experimental or numerical simulation method can be adopted as the research method of choice. Numerical simulation involves constructing a mathematical model of the Solid Oxide Fuel Cell and use of specifically designed software programs that allows the user to manipulate the model to evaluate the system performance under various configurations and in real time. A model is only usable when it is validated with experimental results. Once it is validated, numerical simulation can give accurate, consistent and efficient results. Modeling allows testing and development of new materials, fuels, geometries, operating conditions without disrupting the existing system configuration. In addition, it is possible to measure internal variables which are experimentally difficult or impossible to measure and study the effects of different operating parameters on power generated, efficiency, current density, maximum temperatures reached, stresses caused by temperature gradients and effects of thermal expansion for electrolytes, electrodes and interconnects. iv Since Solid Oxide Fuel Cell simulation involves a large number of parameters and complicated equations, mostly Partial Differential Equations, the situation calls for a sophisticated simulation technique and hence a Finite Element Method (FEM) multiphysics approach will be employed. This can provide three-dimensional localized information inside the fuel cell. For this thesis, COMSOL Multiphysics® version 4.2a will be used for simulation purposes because it has a Batteries & Fuel Cells module, the ability to incorporate custom Partial Differential Equations and the ability to integrate with and utilize the capabilities of other tools like MATLAB ® , Pro/Engineer® , SolidWorks® . Fuel Cells can be modeled at the system or stack or cell or the electrode level. This thesis will study Solid Oxide Fuel Cell modeling at the cell level. Once the model can be validated against experimental data for the cell level, then modeling at higher levels can be accomplished in the future. Here the research focus is on Solid Oxide Fuel Cells that use hydrogen as the fuel. The study focuses on solid oxide fuel cells that use 3-layered, 4-layered and 6-layered electrolytes using pure YSZ or pure SCSZ or a combination of layers of YSZ and SCSZ. A major part of this research will be to compare SOFC performance of the different configurations of these electrolytes. The cathode and anode material used are (La0.6Sr0.4)0.95-0.99Co0.2Fe0.8O3 and Ni-YSZ respectively

The demand of smaller and portable electronic devices has contributed to the realisation of compact embedded systems using PCB miniaturization techniques. The commercial market is faced with competition of handheld users’ devices in medical, communication and automotive industries which are smaller and lighter electronic devices. The possibilities of higher degree of integration in planar technology using cost effective electronic components has lead to different art of design and fabrication of compact units. In this work, a central station and a base station front-end with small form factor have been realized using commercial components on PCBs. These electronic compacts units were integrated in the IF-over-Fiber system architecture. The IF-over-Fiber architecture comprised of miniaturized electronic components for quadrature modulation and upconversion. The central station supports multi-Gbps data rate modulation formats in order to increase the spectral efficiency of the transmitted information. Multilevel modulation formats are considered spectrally efficient and can double the transmission capacity by transmitting more information in the amplitude, phase, polarization or a combination of all. The BS front-end comprises of the 60 GHz upconverter and a 60 GHz planar 2×2 microstrip antenna. The 10 GHz IF carrier allows an optical transmission with higher spectral efficiency in optical domain, as well as it is less susceptible to dispersion induced power fading inherent in optical fiber. Characterization of the designed central station and base station front-end through measurements are presented and discussed. The IF-over-Fiber system analysis is made for the 2 Gbps QPSK transmission with respect to error vector magnitude (EVM), eye and constellation diagrams.

<p> This dissertation is concerned with establishing the conditions under which planar phase interfaces are morphologically unstable during phase transformations in isothermal ternary systems. First, linear perturbation methods are employed in a detailed treatment of precipitatematrix interface stability for dilute ternary systems. Following this, the stability of the planar interface in a two-phase ternary diffusion couple is examined with the aid of perturbation theory. An experimental investigation into the stability of <alpha>-<beta> phase interfaces in the Cu-Zn-Ni system at 775°C is described. The results of this experimental study are shown to be in good agreement with the earlier theoretical predictions. </p> / Thesis / Doctor of Philosophy (PhD)

<p> A method for tlie dynamic analysis· of planar coupled shear walls subjected to ground motions is developed herein. The method is capable of application to nonuniform coupled shear walls resting on flexible foundations. The possibility-of development of yield hinges at the ends of the connecting beams is included in the analysis . Also P-& Effect is incorporated in the stiffness of the structure. </p> <p> The method is based on the transfer matrix technique in combination with the continuum method. A step-by-step integration approach is used in solving the equation of motion. The response to a number of earthquake records are obtained. The effect of the rotational ductility factor of connecting beams is studied. </p> / Thesis / Master of Engineering (MEngr)

Metamaterials are humanly engineered artificial electromagnetic materials which produce electromagnetic properties that are unusual, yet can be observed readily in nature. These unconventional properties are not a result of the material composition but rather of the structure formed. The objective of this thesis is to investigate and design smaller and wideband metamaterial-inspired antennas for personal communication applications, especially for WiMAX, lower band and higher band WLAN applications. These antennas have been simulated using HFSS Structure Simulator and CST Microwave Studio software. The first design to be analysed is a low-profile metamaterial-inspired CPW-Fed monopole antenna for WLAN applications. The antenna is based on a simple strip loaded with a rectangular patch incorporating a zigzag E-shape metamaterial-inspired unit cell to enable miniaturization effect. Secondly, a physically compact, CSRR loaded monopole antenna with DGS has been proposed for WiMAX/WLAN operations. The introduction of CSRR induces frequency at lower WLAN 2.45 GHz band while the DGS has provided bandwidth enhancement in WiMAX and upper WLAN frequency bands, keeping the radiation pattern stable. The next class of antenna is a compact cloud-shaped monopole antenna consisting of a staircase-shaped DGS has been proposed for UWB operation ranges from 3.1 GHz to 10.6 GHz. The novel shaped antenna along with carefully designed DGS has resulted in a positive gain throughout the operational bandwidth. Finally, a quad-band, CPW-Fed metamaterial-inspired antenna with CRLH-TL and EBG is designed for multi-band: Satellite, LTE, WiMAX and WLAN.

The objectives of this work are to review, investigate and model the microwave planar filters of the modern wireless communication system. The recent main stream of microwave filters are classified and discussed separately. Various microwave filters with detailed applications are investigated in terms of their geometrical structures and operational performances. A comprehensive theoretical study of microwave filters is presented. The main types of microwave filters including the basic low-pass filters such as Butterworth and Chebyshev filters are fully analysed and described in detail. The transformation from low-pass prototype filters to high-pass filters, band-pass filters and band-stop filters are illustrated and introduced. Research work on stepped impedance resonator (SIR) and asymmetric stepped impedance resonator (ASIR) structure is presented. The characteristics of λg/4, λg/2 and λg (λg is the guided wavelength of the fundamental frequency in the free space) type SIR resonators, and the characteristic of asymmetric SIR resonator are categorized and investigated. Based on the content mentioned above, novel multi-standard high performance asymmetric stepped impedance resonator single-wideband and dual-wideband filters with wide stopbands are proposed. The methodologies to realize wide passband and wide stop-band filters are detailed. In addition, multi-standard high performance triplewideband, quadruple-wideband and quint-wideband filters are suggested and studied. The measurement results for all prototype filters agree well with the theoretical predictions and simulated results from Ansoft HFSS software. The featured broad bandwidths over single/multiple applicable frequency bands and the high performances of the proposed filters make them very promising for applications in future multistandard wireless communication.

The main objective of this research is to design, model and implement several antenna geometries using electromagnetic band gap (EBG) material and a defected ground plane. Several antenna applications are addressed with the aim of improving performance, particularly the mutual coupling between the elements. The EBG structures have the unique capability to prevent or assist the propagation of electromagnetic waves in a specific band of frequencies, and have been incorporated here in antenna structures to improve patterns and reduce mutual coupling in multielement arrays. A neutralization technique and defected ground plane structures have also been investigated as alternative approaches, and may be more practical in real applications. A new Uni-planar Compact EBG (UC-EBG) formed from a compact unit cell was presented, giving a stop band in the 2.4 GHz WLAN range. Dual band forms of the neutralization and defected ground plane techniques have also been developed and measured. The recorded results for all antenna configurations show good improvement in terms of the mutual coupling effect. The MIMO antenna performance with EBG, neutralization and defected ground of several wireless communication applications were analysed and evaluated. The correlation coefficient, total active reflection coefficient (TARC), channel capacity and capacity loss of the array antenna were computed and the results compared to measurements with good agreement. In addition, a computational method combining Genetic Algorithm (GA) with surface meshing code for the analysis of a 2×2 antenna arrays on EBG was developed. Here the impedance matrix resulting from the meshing analysis is manipulated by the GA process in order to find the optimal antenna and EBG operated at 2.4 GHz with the goal of targeting a specific fitness function. Furthermore, an investigation of GA on 2×2 printed slot on DGS was also done. / Ministry of Higher Education Malaysia and Universiti Tun Hussein Onn Malaysia (UTHM)