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In this study, ultra-performance liquid chromatography was used to quantify the content of alpha acids in hops grown in Nelson, Canterbury and Southland. This method used a binary solvent system consisting of (1) 100% methanol (A) and (2) 85% of solvent A and 15% of solvent B. B is 0.17% v/v formic acid and water. Analysis was performed isocratically at a flowrate of 0.2 mL/min. Separation was achieved on the column of Acquity UPLC® BEH C18, 50 x 2.1 mm, with a particle size of 1.7μm, and with a Acquity UPLC® BEH C18 1.7μm, VanGuard™ pre-column 5 x 2.1 mm. The compounds of interest eluted within 4 mins. The results of this experimental study show that the content of alpha acids in hops is not only related to the growth environment but also related to the variety.

The active materials of lithium-ion batteries exhibit volumetric deformation during lithium intercalation and de-intercalation. Stress stemming from this volume change affects not only the durability of the batteries, but also the electrochemical processes in the electrode. This dissertation focuses on the mechanical and electrochemical modeling and design of lithium-ion batteries, ranging from particle scale to electrode scale. Many electrode materials for lithium-ion battery applications are composed of secondary particles. Such an active material particle is not a solid particle, but consists of many fine primary particles. A mechanical and electrochemical coupled model is developed to simulate the intercalation-induced stress in a secondary particle with the agglomerate structure. In this model the electrochemical and transport processes are accounted for at both the secondary and primary particle levels. For mechanical analysis the secondary particle is treated as a continuum with stress calculated through lithium concentration and elastic deformation. Several important factors that affect stresses in secondary particles are revealed with this model. Active particles with a core–shell structure exhibit superior physical, electrochemical, and mechanical properties over their single-component counterparts in electrodes. A physically rigorous model is developed to describe the diffusion and stress inside the core-shell structure based on a generalized chemical potential. Including both chemical and mechanical effects, the generalized chemical potential governs the diffusion in both the shell and the core. The stress is calculated using the lithium concentration profile. As revealed by the simulations, the core–shell interface is prone to debonding for particles with a thick shell, while shell fracture is more likely to occur for particles with a large core and a relatively thin shell. Based on the simulation results, a design map of the core and shell sizes is generated to avoid both shell fracture and core-shell debonding. As an inherent multiscale structure, a continuum scale battery electrode is composed of many microscale particles. A multiscale model is developed to couple mechanics and electrochemistry consistently at the microscopic and continuum scales. The microscopic particle stress is treated as a superposition of the intra-particle concentration gradient-induced stress and the particle interaction stress, with the latter being related to the continuum scale stress through a representative volume element. Solid diffusion and charge transfer kinetics are generalized with the mechanical effect. In a parallel effort, a direct three-dimensional particle network model is developed to serve as a standard. Comparison of results from the multiscale model and from the particle network model shows that the multiscale model gives good, satisfying accuracy with dramatically reduced computational cost. Simulation-based battery design encounters the difficulty of high computational cost. A systematic approach based on the artificial neural network is developed to reduce the computational burden of simulation based battery design. Two neural networks are constructed using the finite element simulation results from a thermo-electrochemical model. The first neural network serves as a classifier to predict whether a set of input variables is physically feasible. The second neural network yields specific energy and specific power. With a global sensitivity analysis using the neural networks, the effects of input variables on specific energy and specific power are quantified, which is computationally prohibitive for finite element simulations. A design map is generated to fulfill the requirements of both specific energy and specific power.

Voltage boosting is required in many energy conversion applications, ranging from front-end solar energy system to Medium-Voltage DC (MVDC)-grid system, and from headlamp ballast of automobile to fuel cell powered system. This dissertation is dedicated to the development of voltage boosting technology. New circuits were found both in switched capacitor converters and inductor-based power converters. The former has the potential of full integration while the latter has combined the merits of conventional magnetic components and switched capacitor stages, leading to a new hybrid converter category. These contributions are captured in two major parts respectively: The first part discusses the switched capacitor converters and new discovery in voltage boosting technology as well as modeling technique. The second part introduces a number of new topologies and extensions in hybrid boosting converters.Part I Switched Capacitor Converter (SCC) is a special branch of power electronics converters which is composed of capacitors and switches without the participation of inductors/transformers. It potentially has lower electromagnetic interference (EMI), lighter weight, lower cost, higher energy density, and the promise for full integration. In this part, a family of "Two-switch Boosting Switched-capacitor Converters (TBSC)" is introduced, which distinguishes itself from the prior arts by its symmetrical interleaved operation, reduced output ripple, low yet even voltage stress on components, and systematic expandability. Along with the topologies, a modeling technique based on charge-balance transient-calculation is formulated, which provokes the converter regulation method through duty cycle and frequency adjustment. The design guideline for high efficient TBSC is provided and regulation under high power condition is explored. In addition, an enhanced accurate modeling technique considering the output capacitor effect is developed for simple two-phase SC converters.Part II Built upon the momentum of the "Two-switch Boosting Switched-capacitor Converters (TBSC)" circuit structure, another family of Hybrid Boosting Converters (HBC) is developed, featuring wide regulation range, symmetrical configuration, low component voltage stress, small output voltage ripple, and expandable structure. It integrates the inductive switching cores of various functionalities and control strategies with Bipolar Voltage Multiplier (BVM), resulting in the new breed of hybrid converters: Hybrid Boosting Converters (HBC). The proposed HBC family includes the basic HBC, symmetrical HBC, Isolated HBC, and tapped inductor HBC, all of which are analyzed in details and design considerations are provided. In addition, the 3D DC-DC converter concept for high power application, inverter configuration and DC micro-grid based on HBC converters are developed. The proposed HBCs are applicable in many areas such HID lamp driver, X-ray system, ion pumps, front-end photovoltaic energy system, and energy storage systems.

Internal combustion engines experience a wide range of operating conditions, thus requiring design compromises to achieve satisfactory overall performance. However, there is strong motivation to make fixed parameters variable, permitting design constraints to be relaxed. This increases the system complexity due to increased degrees of freedom and complicated interactions among these independent control variables. Developing controllers and calibration maps becomes increasingly challenging, as the total number of experiments required for calibration increases exponentially with the number of independent control variables. Hence, the traditional calibration methodology, which generates look-up tables through systematic sweep tests, becomes prohibitively expensive. This study answers the challenge imposed by high degrees of freedom through development of a simulation-based algorithm. A high-fidelity engine simulation tool is developed to predict engine performance corresponding to different control variable combinations. Pre-optimality studies are conducted to generate high-fidelity simulation benchmarks. Since optimization is very computation-intensive, it is not feasible to use the high-fidelity tool for solving optimization problems directly. Instead, Artificial Neural Networks (ANN) trained with high-fidelity simulation results are used as surrogate models. The ANNs are shown to be capable of representing complex relationships between multiple independent variables and selected engine performance indicators, such as brake torque, fuel consumption, NOx emissions, etc. Finally, the ANN surrogate models are employed in the optimization framework that searches the optimal combination of setpoints for any given driving condition. The proposed algorithm is demonstrated on a conventional port-injected Spark-Ignition (SI) engine with two additional degrees of freedom introduced by the dual independent Variable Valve Timing (VVT) mechanism. The intake and exhaust camshaft positions are optimized for both wide open throttle and part load, using the appropriate combinations of optimization objectives and constraints. In addition, the capability of generating fast ANN models is utilized for developing a real-time air mass flow rate estimator for a VVT engine. With proper adaptation, the algorithm can be extended for complex engine and powertrain systems with even more degrees of freedom.

Twin-core rare-earth doped nonlinear optical fiber devices, including optical fiber switches, optical fiber filters and optical fiber amplifiers, are explored in this thesis. An analytical method resorting to the energy E of an oscillator with perturbed nonlinear potential is proposed and demonstrated for investigating the bifurcation and the near-separatrix-crossing of a nonlinear fiber coupler with loss and saturable nonlinearity. Two characteristic equations for bifurcation and near-separatrix-cros sing are obtained, from which the critical optical power, the minimum coupling length and the maximum coupler length can be decided. These two equations can be used as the design criteria of a nonlinear fiber coupler with loss and saturable nonlinearity. The techniques of fabrication and measurement of twin-core rare-earth doped nonlinear fibers are described. The nonlinear refractive index coefficients in erbium or neodymium doped fibers are determined using two core fibers in which only one core is doped. The nonlinearity caused by population redistribution in rare-earth doped fibers is wavelength-dependent. Moreover, the nonlinear saturation effect is observed. The all-optical fiber switch constructed from a twin-core erbium-doped fiber is studied theoretically and experimentally. The switching behaviour is simulated theoretically, and a switching fraction of 65% is obtained experimentally. The advantage of this switch is that it requires only a fraction of a milliwatt of input power to switch. The transient switching experiment indicates that the switching response time is in the order of 10 ms. Furthermore, a compact optical switching device through the use of a twin-core Nd3+-doped fiber coupler and a laser diode is demonstrated. Steady state switching and transient switching is obtained. The switching power is 5.6 mW and the switching speed is 500 p.s which is 20 times faster than that in twin-core Er^-doped fiber couplers. In addition to the passive fiber devices, an active twin-core rare-earth doped fiber coupler is proposed and studied theoretically. It is demonstrated both numerically and experimentally that a narrow-band wavelength filter/demultiplexer with gain can be constructed from a twin-core rare-earth-doped fiber. The experimental bandwidth obtained is 6.5 nm. In addition, the filtered signal experiences a gain of 20 dB instead of attenuation. A preliminary study of using light to control light has been carried out. Optical signal switching through the use of a pump light is observed. Finally, a theoretical model has been proposed in that a twin-core erbium-doped fiber can be used as an optical fiber amplifier. Its gain spectrum is flat within 2.5 dB in a bandwidth of 30 nm. This gain spectrum can be adjusted continuously by varying the pump power launched into one of the cores.

To further enhance the progress made by its manufacturing industries during the last two decades, the Sixth Development Plan of Saudi Arabia has stressed the importance of diversifying the country’s economic base, reducing its dependence on the production and export of crude oil, and increasing the industrial sector’s contribution to GDP. Since national level industrial policies cannot succeed without the full participation and support of the individual companies, it is necessary for its manufacturing organisations to adopt appropriate methods for increasing their overall competitiveness. This research is concerned with the development of a methodology for manufacturing strategy formulation to help Saudi companies achieve competitiveness in both the local and the international market environment. The work has resulted in a prototype methodology known as MSAMSA - a Methodology of Manufacturing Strategy Analysis for the Manufacturing Industries in Saudi Arabia. The basic concepts of MSAMSA is based on a framework developed previously by the CAMSD research team at Cranfield University, UK. However, the structure and procedures have been further developed to reflect Saudi-specific requirements, and to help link the country’s long-term industrial policy to the medium-term strategic direction of the individual companies. In particular, MSAMSA adopts a generic, extended scheme of manufacturing strategy evaluation, tackling a number of key requirements such as: the need for a more structured way to coherently link strategic policies at different levels, and the need to provide both local- level (internal) and global-level (external) measures to prioritise and evaluate strategic concerns. Industrial case studies have shown that MSAMSA’s approach and compatibility with the current national level policies are both timely and conceptually logical. In addition, these have also highlighted issues which may be of value to the authorities’ future decision-making. Therefore the methodology’s further enhancement and application are anticipated to be of national importance. Due to its generic nature, it should be possible to adopt the extended scheme to satisfy the needs of manufacturing companies within different industrial sectors or even in different countries.