Polyferrocenylsilane (PFS) diblock copolymers self-assemble in selective solvents to form one-dimensional micelles for a broad range of polymer compositions and experimental conditions, driven by the crystallization of the PFS block that forms the micelle core. The most striking feature of these micelles is that they remain active for further growth. They can be extended in length when additional polymer, dissolved in a good solvent, is added to a solution of the pre-existing micelles. This thesis describes several studies investigating the factors that affect the growth and fragmentation of PFS diblock copolymer micelles in solution, with a particular emphasis on polyisoprene-PFS (PI-PFS) diblock copolymers. The goal of my research was trying to provide deeper understanding of this crystallization-driven self-assembly (CDSA) process. In an attempt to understand the growth kinetics of the PI-PFS cylindrical micelles, I added tiny amount of short micelle seeds into supersaturated solution of the same polymer, and followed the micelle growth by light scattering. The data analysis showed that the increase of micelle length could be described by an expression with two exponential decay terms. In another attempt to examine the factors that may affect the growth behavior of the PI-PFS micelles, I found that PI-PFS long micelles underwent fragmentation when they were subjected to external stimuli, e.g. addition of polar solvent, or heating. During the course of studying the effect of heating on the micelles, I developed a new approach to generate cylindrical micelles with controllable and uniform length, a one-dimensional analogue of self-seeding of crystalline polymers. I carried out a systematic study to investigate the self-seeding behavior of PFS block copolymers.

The interaction of nanoparticles with biological systems, especially interactions with cell membranes, has been a subject of active research due to its numerous applications in many areas of soft-matter and biological systems. Within only a few relevant physical parameters profound structural properties have been discovered in the context of simple coarse-grained theoretical models. In this Thesis we study the structure of a tubular membrane adhering to two rigid cylindrical particles on a basis of a free-energy model that uses Helfrich energy for the description of the membrane. A numerical procedure is developed to solve the shape equations that determine the state of lowest energy. Several phase transitions exist in the system, arising from the competition between the bending energy of the membrane and the adhesion energy between the membrane and the particles. A continuous adhesion transition between the free and bound states, as well as several discontinuous shape transitions are identified, depending on the physical parameters of the system. The results are then generalized into a single phase diagram separating free, symmetric- and asymmetric-wrapping states in the phase space of the size of the particles and the adhesion energy. We show that for a relatively small size of the membrane tube the interaction between the cylinders becomes attractive in the strong curvature regime, leading to aggregation of the particles in the highly curved area of the tube that is characteristically different from the aggregation in a related three-dimensional system. For a relatively large membrane tube size the cylinders prefer to have a non-zero separation, even in the completely engulfed state. This indicates that, i) the spontaneous curvature of the membrane may play a role in the sign of the interaction of two colloidal particles adhered to a membrane and ii) cylindrical particles can aggregate on membrane tubes and vesicles if the curvature of the membrane around the aggregation region is sufficiently large.

Natural convection with high cooling effects is of increasing interest in cold region geotechnical engineering. To study natural air convection in a highly-permeable porous medium, convective and conductive heat transfer experiments were carried out using an insulated cylindrical tank filled with styrofoam chips. Convection and conduction were caused by controlling the temperatures at the top and bottom of the tank, and a series of cross-sectional conductive and convective isotherms were generated from collected temperature data. Additional convective patterns were obtained from tests by centrally localized heating below or cooling above. Flow velocities were measured at the center of the tank. Results showed that convective heat transfer rate was higher than thermal conduction. Convective isothermal patterns varied with various boundary conditions and could be influenced by small temperature perturbation. Given appropriate environmental conditions, efficient convective cooling effects can be used to enhance ground freezing or to protect permafrost from degradation. / Geotechnical Engineering

vii, 99 p. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / We investigate Cesàro summability of the Fourier orthogonal expansion of functions on B d × I m , where B d is the closed unit ball in [Special characters omitted] and I m is the m -fold Cartesian product of the interval [-1, 1], in terms of orthogonal polynomials with respect to the weight functions (1 - z ) α (1 + z ) β (1 - |x| 2 ) λ-1/2 , with z ∈ I m and x ∈ B d . In addition, we study a discretized Fourier orthogonal expansion on the cylinder B 2 × [-1, 1], which uses a finite number of Radon projections. The Lebesgue constant of this operator is obtained, and the proof utilizes generating functions for associated orthogonal series. / Committee in charge: Yuan Xu, Chairperson, Mathematics; Huaxin Lin, Member, Mathematics Jonathan Brundan, Member, Mathematics; Marcin Bownik, Member, Mathematics; Jun Li, Outside Member, Computer & Information Science

The interaction between water waves and a floating or fixed body is bi-directional: wave forces act on and cause motion in the body, and the body alters the wave field. The impact of the body on its wave field is important to understand because: 1) it may have positive or negative consequences on the natural or built environment; 2) multiple bodies in proximity interact via the waves that are scattered and radiated by them; and 3) in ocean wave energy conversion, by conservation of energy, as a device absorbs energy, so too must the energy be removed from the wave field. Herein, the cylindrical solutions to the linear wave boundary-value problem are used to analyze the floating body wave field. These solutions describe small-amplitude, harmonic, potential-flow waves in the form of a Fourier summation of incoming and outgoing, partial, cylindrical, wave components. For a given geometry and mode of motion, the scattered or radiated waves are characterized by a particular set of complex cylindrical coefficients. A novel method is developed for finding the cylindrical coefficients of a scattered or radiated wave field by making measurements, either computationally or experimentally, over a circular-cylindrical surface that circumscribes the body and taking a Fourier transform as a function of spatial direction. To isolate evanescent modes, measurements are made on the free-surface and as a function of depth. The technique is demonstrated computationally with the boundary-element method software, WAMIT. The resulting analytical wave fields are compared with those computed directly by WAMIT and the match is found to be within 0.1%. A similar measurement and comparisons are made with experimental results. Because of the difficulty in making depth-dependent measurements, only free-surface measurements were made with a circular wave gauge array, where the gauges were positioned far from the body in order to neglect evanescent modes. The experimental results are also very good. However, both high-order harmonics and wave reflections led to difficulties. To compute efficiently the wave interactions between multiple bodies, a well-known multiple-scattering theory is employed, in which waves that are scattered and radiated by one body are considered incident to another body, which in turn radiates and scatters waves, sending energy back to the first. Wave fields are given by their cylindrical representations and unknown scattered wave amplitudes are formulated into a linear system to solve the problem. Critical to the approach is the characterization of, for each unique geometry, the cylindrical forces, the radiated wave coefficients, and the scattered waves in the form of the diffraction transfer matrix. The method developed herein for determining cylindrical coefficients is extended to new methods for finding the quantities necessary to solve the interaction problem. The approach is demonstrated computationally with WAMIT for a simple cylinder and a more complex wave energy converter (WEC). Multiple-scattering computations are verified against direct computations from WAMIT and are performed for spectral seas and a very large array of 101 WECs. The multiple-scattering computation is 1,000- 10,000 times faster than a direct computation because each body is represented by 10s of wave coefficients, rather than 100s to 1,000s of panels. A new expression for wave energy absorption using cylindrical coefficients is derived, leading to a formulation of wave energy absorption efficiency, which is extended to a nondimensional parameter that relates to efficiency, capture width and gain. Cylindrical wave energy absorption analysis allows classical results of heaving and surging point absorbers to be easily reproduced and enables interesting computations of a WEC in three-dimensions. A Bristol Cylinder type WEC is examined and it is found that its performance can be improved by flaring its ends to reduce "end effects". Finally, a computation of 100% wave absorption is demonstrated using a generalized incident wave. Cylindrical representations of linear water waves are shown to be effective for the computations of wave-body wave fields, multi-body interactions, and wave power absorption, and novel methods are presented for determining cylindrical quantities. One of the approach's greatest attributes is that once the cylindrical coefficients are found, complex representations of waves in three dimensions are stored in vectors and matrices and are manipulated with linear algebra. Further research in cylindrical water waves will likely yield useful applications such as: efficient computations of bodies interacting with short-crested seas, and continued progress in the understanding of wave energy absorption efficiency.

As the wireless communications networks expand, the number of both unwanted directional interferences and strong nearby sources increase, which degrade system performance. The signal-tointerference ratio (SIR) can be improved by using multiple nulls in the directions of the interferences while maintaining omnidirectional coverage in the direction of the network users. For the communication system considered, the interferences are static and their spatial positions are known. A non-adaptive antenna array is needed to provide spatial filtering in a static wireless environment. Omnidirectional arrays, such as cylindrical arrays, are the most suitable to provide the omnidirectional coverage and are capable of suppressing interferences when nulls are inserted in the radiation pattern. In this thesis, a cylindrical microstrip patch antenna array is investigated as an antenna to provide an omnidirectional radiation pattern with nulls at specified angular locations to suppress interference from directional sources. Three null synthesis methods are described and used to provide the omnidirectional array pattern with nulls using the radiation characteristics of the cylindrical microstrip patch antenna elements. The orthogonal projection method is extended to incorporate the directive radiation patterns of the cylindrical microstrip patch elements. Using this method, an optimal pattern that minimises the squared pattern error with respect to the ideal pattern is obtained. Instead of only minimising the array pattern error, a multi-objective optimisation approach is also followed. The objective weighting method is applied in null pattern synthesis to improve the amplitude pattern characteristics of the cylindrical patch arrays. As a third null synthesis technique, a constraint optimisation method is applied to obtain a constrained pattern with the desired amplitude pattern characteristics. The influence of the array attributes on the characteristics of the amplitude patterns obtained from the null synthesis methods, is also studied. In addition, the implementation of the cylindrical microstrip patch array is investigated. The influence of the mutual coupling on the characteristics of the null patterns of the cylindrical patch arrays is investigated utilising simulations and measurements. A mutual coupling compensation technique is used to provide matched and equal driving impedances for all the patch antenna elements given a required set of excitations. Test cases in which this technique is used, are discussed and the consequent improvements in the bandwidth and reflection coefficient of a linear patch arrays are shown. The characteristics of the resulting null pattern for the cylindrical microstrip patch array is also improved using the compensation technique. / Thesis (PhD (Electronic Engineering))--University of Pretoria, 2006. / Electrical, Electronic and Computer Engineering / unrestricted

A new angles-only initial relative orbit determination (IROD) algorithm is derived using three line-of-sight observations. This algorithm accomplishes this by taking a Singular Value Decomposition of a 6x6 matrix to arrive at an approximate initial relative orbit determination solution. This involves the approximate solution of 6 polynomial equations in 6 unknowns. An iterative improvement algorithm is also derived that provides the exact solution, to numerical precision, of the 6 polynomial equations in 6 unknowns. The initial relative orbit algorithm is also expanded for more than three line-of-sight observations with an iterative improvement algorithm for more than three line-of-sight observations. The algorithm is tested for a range of relative motion cases in low earth orbit and geosynchronous orbit, with and without the inclusion of J2 perturbations and with camera measurement errors. The performance of the IROD algorithm is evaluated for these cases and show that the tool is most accurate at low inclinations and eccentricities. Results are also presented that show the importance of including J2 perturbations when modelling the relative orbital motion for accurate IROD estimates. This research was funded in part by the Air Force Research Lab, Albuquerque, NM.

Energy enables basic and innovative services to reach a seemingly ever-growing population and when its generation costs are reduced or when its usage is optimized it has the greatest impact on the reduction of poverty. Furthermore, there is a pressing need to decouple energy generation from non-renewable and carbon-heavy sources which has led mayor economies to increase research efforts in these areas. This thesis discusses research on water oxidation using nanostructured iron oxide electrodes and current-induced magnetic domain wall motion in nickel/cobalt bi-segmented nanowires. These two fields may seem disparate at first glance, but are linked by such common theme: materials for energy, and more precisely, materials for energy conversion and economy. The work presented in this document aims also to reflect this theme by using widely available materials like iron and aluminum, and optimizing the methods to produce the final samples using the least resources possible. All samples were prepared by electroplating metals (iron, cobalt and nickel) into anodized alumina templates fabricated inhouse. For water oxidation, iron nanorods were integrated into an electrode and annealed in air, while nickel/cobalt nanowires were isolated and contacted individually to test for spintronics-related effects. Spintronic-based devices aim to reduce energy usage in nowadays microelectronic devices. The nanostructured iron oxide electrode showed its usefulness for water oxidation in a laboratory environment, making it an appropriate complement to other electrodes specially designed for water reduction in a photoelectrochemical cell. This two-electrode design, allows for hydrogen and oxygen to be produced at each electrode and therefore eases their separate collection for, e.g., fuel or fertilizers. On the other hand, this work presents one of the first experimental demonstration of current-induced domain wall motion in soft/hard cylindrical magnetic nanowires at zero applied external magnetic field. These kinds of experiments are expected to be the first of many which will allow researchers in the field to test for spintronic-relevant properties and interactions in cylindrical magnetic nanowires.

No description available.

I processen att optimera och elektrifiera fordon som använder sig utav batterier har litiumjon battericeller introducerats till fordonen. Det vanligaste sättet är att tillverkaren installerar en stor battericell (> 10 Ah) i fordonen. En stor cell har många fördelar mot en liten cell, som att den är lättare att hantera, den utrustning som krävs för att övervaka cellen blir mindre och det krävs inga kopplingar mellan flertal celler. Det finns däremot en mängd fördelar med att ha mindre celler (< 5 Ah). De mindre cellerna skulle kunna bidra till en lägre kostnad, en jämnare värmefördelning över systemet och framförallt lättare att mekaniskt installera fordonet. Det vanligaste är att företag använder sig utav de större cellerna, det finns däremot fåtal exempel i privata fordonssektorn där tillverkare använder sig utav de mindre cellerna. Att använda sig utav de mindre cellerna kräver ett annat tänk när det gäller kylning, paketering i fordonen samt bevakningen av cellernas hårdvara och mjukvara blir annorlunda. Detta projekt har fokuserat på de elektriska och termiska aspekterna för implementering av parallellt kopplade små litiumjonceller i tunga fordon, som bussar och lastbilar. I projektet utfördes prestandaprov där temperatur, spänning och ström monitorerades över cellerna. Syftet var att öka kunskapen inom området för dessa små celler för att se om dessa har en potentiell plats på den kommersiella marknaden i framtiden. Målet med detta projekt är att mäta den spridning av ström som sker mellan de parallellt kopplade cellerna under variering av temperatur mellan cellerna. Från de utförda experimenten syns det tydligt att det sker en spridning av strömmen mellan cellerna. Den temperaturskillnaden som testas under experimentet påverkar inte strömmens spridning tillräckligt för att det ska visa någon differens i strömspridningen mellan cellerna. Detta ledde till att slutsatsen för projektet blir att det sker en strömspridning mellan parallellt kopplade celler, men temperaturdifferensen på tio grader celsius är inte tillräcklig för att påverka cellerna så pass att spridningen blir större. Under projektets gång möttes vi av många utmaningar och svårigheter. Detta har gjorde att den tid som kunde spenderas på provfasen blev väldigt kort. Det ufördes därför en minimal mängd av prov, vilket betyder att den data som samlades in under projektet inte var lika omfattande som det från början önskats. / In the process of optimizing and electrifying vehicles using batteries, lithium-ion battery cells have been introduced to the vehicles. The most common way is that the manufacturer installs a large battery cell (> 10 Ah) in the vehicles. A large cell has many advantages to a small cell. For example it is easier to handle, the equipment required to monitor the cell becomes smaller and no connections between multiple cells are required. On the other hand, there are many advantages of having smaller cells (<5 Ah). The smaller cells could contribute to a lower cost, a more even heat distribution across the system and, above all, easier to mechanically install in the vehicle. The most common choice for companies is to use the larger cells, but there are few examples in the private vehicle sector where manufacturers use the smaller cells. Using the smaller cells requires a different idea when it comes to cooling the cells, packing in the vehicles, and monitoring the hardware and software of the cells are different. This project focused on the electrical and thermal aspects of implementing parallel-connected small lithium-ion cells in heavy vehicles, such as buses and lorries. In this project performance tests were performed where temperature, voltage and current are monitored across the cells. The aim was to increase knowledge in the area of these small cells, to see if they have a potential place in the commercial market in the future. The goal of this project was to measure the spread of current that occurs between the parallel-connected cells during the varying temperature between the cells. From the experiments carried out, it was clear that there’s a spread of the current between the cells. The temperature difference tested during the experiment does not affect the spread of the current enough to show any difference in the current spread between the cells. Which leads to the conclusion of the project that there are a current spread between parallelconnected cells. However, the temperature difference of ten degrees Celsius is not sufficient to affect the cells enough that the spread becomes larger. The project faced a lot of challenges and difficulties. This has meant that the time spent on the experimental phase became very short. Therefore, a minimal amount of experiments was completed, which in turn means that the data collected for the project is not as extensive as it was meant to be initially.