Computational aspects of a three dimensional non-intrusive particle motion tracking system

Development of a technique for non-intrusive particle motion tracking in three dimensions is considered. This technique is based on the principle of magnetic induction. In particular, the determination of the position and onentation of the particle from the information gathered is the pnncipal focus of this thesis. The development of such a system is motivated by the need to understand the flow patterns of granular material. This is of cntical importance in dealing with problems associated with bulk solids flows which occur in almost all industries and in natural geological events. A study of the current diagnostic techniques reveals the limitations in their ability to track the motion of an individual particle in a mass flow of other particles. These techniques fail when the particle must be tracked in three dimensions in a non-intrusive manner. The diagnostic technique we consider results in an unconstrained minimization problem of an overdetennined system of nonlinear equations. The Levenberg-Marquardt algorithm is used to solve such a system to predict the location of the particle. The viability of this technique is established through simulated and actual expenmental results. Practical problems such as the effect of noise are considered. Directions for future work are provided

Understanding Trade-offs in Stellarator Design with Multi-objective Optimization

In designing stellarators, any design decision ultimately comes with a trade-off. Improvements in particle confinement, for instance, may increase the burden on engineers to build more complex coils, and the tightening of financial constraints may simplify the design and worsen some aspects of transport. Understanding trade-offs in stellarator designs is critical in designing high performance devices that satisfy the multitude of physical, engineering, and financial criteria. In this study we show how multi-objective optimization (MOO) can be used to investigate trade-offs and develop insight into the role of design parameters. We discuss the basics of MOO, as well as practical solution methods for solving MOO problems. We apply these methods to bring insight into the selection of two common design parameters: the aspect ratio of an ideal magnetohydrodynamic equilibrium, and the total length of the electromagnetic coils

Direct stellarator coil design using global optimization: application to a comprehensive exploration of quasi-axisymmetric devices

Many stellarator coil design problems are plagued by multiple minima, where the locally optimal coil sets can sometimes vary substantially in performance. As a result, solving a coil design problem a single time with a local optimization algorithm is usually insufficient and better optima likely do exist. To address this problem, we propose a global optimization algorithm for the design of stellarator coils and outline how to apply box constraints to the physical positions of the coils. The algorithm has a global exploration phase that searches for interesting regions of design space and is followed by three local optimization algorithms that search in these interesting regions (a "global-to-local" approach). The first local algorithm (phase I), following the globalization phase, is based on near-axis expansions and finds stellarator coils that optimize for quasisymmetry in the neighborhood of a magnetic axis. The second local algorithm (phase II) takes these coil sets and optimizes them for nested flux surfaces and quasisymmetry on a toroidal volume. The final local algorithm (phase III) polishes these configurations for an accurate approximation of quasisymmetry. Using our global algorithm, we study the trade-off between coil length, aspect ratio, rotational transform, and quality of quasi-axisymmetry. The database of stellarators, which comprises almost 140,000 coil sets, is available online and is called QUASR, for "QUAsi-symmetric Stellarator Repository"

Component based performance simulation of HVAC systems

The design process of HVAC (Heating, Ventilation and Air Conditioning) systems is based upon selecting suitable components and matching their performance at an arbitrary design point, usually determined by an analysis of the peak environmental loads on a building. The part load operation of systems and plant is rarely investigated due to the complexity of the analysis and the pressure of limited design time. System simulation techniques have been developed to analyse the performance of specific commonly used systems: however these 'fixed menu, simulations do not permit appraisal of hybrid and innovative design proposals. The thesis describes research into the development of a component based simulation technique in which any system may be represented by a network of components and their interconnecting variables. The generalised network formulation described is based upon the engineer's schematic diagram and gives the designer the same flexibility in simulation as is available in design. The formulation of suitable component algorithms using readily available performance data is discussed, the models developed being of a 'lumped parameter' steady state form. The system component equations are solved simultaneously for a particular operating point using a gradient based non-linear optimisation algorithm. The application of several optimisation algorithms to the solution of RVAC systems is described and the limitations of these methods are discussed. Conclusions are drawn and recommendations are made for the required attributes of an optimisation algorithm to suit the particular characteristics of HVAC systems. The structure of the simulation program developed is given and the application of the component based simulation procedure to several systems is described. The potential for the use of the simulation technique as a design tool is discussed and recommendations for further work are made

Design of the Annular Suspension and Pointing System (ASPS) (including design addendum)

The Annular Suspension and Pointing System is an experiment pointing mount designed for extremely precise 3 axis orientation of shuttle experiments. It utilizes actively controlled magnetic bearing to provide noncontacting vernier pointing and translational isolation of the experiment. The design of the system is presented and analyzed