<p>Both blind and sighted persons may use echoes for detecting objects.</p><p>The effect of object size on echolocation was tested in a listening</p><p>experiment with 15 sighted participants. Noise burst of 500-ms were</p><p>generated and recorded in an ordinary room, with and without a</p><p>reflecting object. The diameter of the reflecting object was 0.25 or</p><p>0.50 m, and it was located at a distance of 0.5, 1, 2, 3 m from the</p><p>microphones. Pairs of sounds, one with and one without the object,</p><p>were presented to the listeners. Their task was to decide which of the</p><p>two sounds that were recorded with the reflecting object. The results</p><p>showed that it was harder to detect the 0.25 than the 0.5 m object, and</p><p>that performance generally decreased with distance. The auditory</p><p>angle, which is a function of the size to distance ratio, was found to</p><p>predict detection performance fairly well.</p><p>Sighted</p>

<p>Since the discovery in 1977 that conjugated polymers can be doped to achieve almost metallic electronic conduction, the research field of conducting polymers has escalated, with applications such as light emitting diodes, solar cells, thin film transistors, electrochemical transistors, logic circuits and sensors. The materials can be chemically modified during their synthesis in order to tailor the desired mechanical, electronic and optical properties of the final product. Polymers are also generally possible to process from solution, and regular roll-to-roll printing techniques can therefore be used for manufacturing of electronic components on flexible substrates like plastic or paper. On top of that, the nature of conjugated polymers enables the creation of devices with novel properties, which are not possible to achieve by using inorganic materials such as silicon.</p><p>The work presented in this thesis mainly focuses on devices that utilize two rather unique properties of conducting polymers. Conducting polymers are generally electrochromic, i.e. they change color upon electrochemical oxidation or reduction, and can therefore be used as both conductor and pixel element in simple organic displays. As a result of the electrochemical reaction, some polymers also alter their surface properties and have proven to be suitable materials for organic electronic wettability switches. Control of surface wettability has applications in such diverse areas as printing techniques, micro-fluidics and biomaterials.</p><p>The aim of the thesis is to briefly describe the physical and chemical background of the materials used in organic electronic devices. Topics include molecular properties and doping of conjugated polymers, electrochromism, surface tension etc. This slightly theoretical part is followed by a more detailed explanation of device design, functionality and characterization. Finally, a glance into future projects will also be presented.</p> / ISRN/Report code: LiU-TEK-LIC-2005:50

<p>In angle-only target tracking the aim is to estimate the state of a target with use of measurement of elevation and azimuth. The state consists of relative position and velocity between the target and the platform. The platform is an Unmanned Aerial Vehicle (UAV) and the tracking system is meant to be a part of the platform’s anti-collision system. In the case where both the target and the platform travel with constant velocity the angle measurements do not provide any information of the range between the target and the platform. The platform has to maneuver to be able to estimate the range to the target.</p><p>Two filters are implemented and tested on simulated data. The first filter is based on a Extended Kalman Filter (EKF) and is designed for tracking nonmaneuvering targets. Different platform maneuvers are studied and the influence of initial errors and the geometry of the simulation scenario is investigated. The filter is able to estimate the position of the target if the platform maneuvers and the target travels with constant velocity. Maneuvering targets on the other hand can not be tracked by the filter.</p><p>The second filter is an interacting multiple model (IMM) filter, designed for tracking maneuvering targets. The filter performance is highly dependent of the geometry of the scenario. The filter has been tuned for a scenario where the target approaches the platform from the front. In this scenario the filter is able to track both maneuvering and non-maneuvering targets. If the target approaches the platform from the side on the other hand, the filter has problems with distinguish target maneuvers from measurement noise.</p>

We have studied the mechanical properties of monolithic bulk metallic glasses and composite in the La based alloys. La₈₆₋yAl₁₄(Cu, Ni)y (y=24 to 32) alloy systems was used to cast the in-situ structure and subsequently tested under compression. We found that the ductility of the monolithic is actually poorer than that of the fully crystalline composite. / Singapore-MIT Alliance (SMA)

Advanced optical technologies profoundly impact countless aspects of modern life. At the heart of these technologies is the manipulation of light using optical materials. Currently, optical technologies are created using naturally occurring materials. However, a new and exciting approach is to use nanomaterials for technology development. Nanomaterials are artificially constructed material systems with precisely engineered nanostructures. Many technological revolutions await the development of new nanoscale fabrication methods that must provide the ability to control, enhance, and engineer the optical properties of these artificial constructs. This thesis responds to the challenges of nanofabrication by examining glancing angle deposition (GLAD) and improving its optical-nanomaterial fabrication capabilities. GLAD is a bottom-up nanotechnology fabrication method, recognized for its flexibility and precision. The GLAD technique provides the ability to controllably fabricate high-surface-area porous materials, to create structurally induced optical-anisotropy in isotropic materials, and to tailor the refractive index of a single material. These three advantages allow GLAD to assemble optical nanomaterials into a range of complex one-dimensional photonic crystals (PCs). This thesis improves upon previous GLAD optical results in a number of important areas. Multiple optical measurement and modeling techniques were developed for GLAD-fabricated TiO2 nanomaterials. The successful characterization of these nanomaterials was extended to engineer PC structures with great precision and a superior degree of control. The high surface area of basic PC structures was exploited to fabricate an optimized colourimetric sensor with excellent performance. This colourimetric sensor required no power source and no read-out system other than the human eye, making it a highly attractive sensing approach. Incorporating engineered defects into GLAD-fabricated PCs established a new level of design sophistication. Several PC defect structures were examined in detail, including spacing layers and index profile phase-shifts. Remarkable control over defect properties was achieved and intriguing polarization-sensitive optical effects were investigated in anisotropic defect layers. The success of these results demonstrates the precision and flexibilty of the GLAD technique in fabricating optical nanomaterials and advanced photonic devices. / Micro-Electro-Mechanical Systems (MEMS) and Nanosystems

The glancing angle deposition (GLAD) technique is now used by over one hundred research groups, each requiring a fundamental understanding of and new techniques for modulating the properties of GLAD in order to optimize their results. In this thesis, the structural characteristics of nanostructured columnar films were therefore investigated and quantified using gas adsorption porosimetry, focused ion beam tomography, optical methods, scanning electron microscopy (SEM) image analysis. Questions such as ``What is their surface area?'', ``How porous are they?'', ``How do the films evolve as they grow?'', and ``Can the structural characteristics be manipulated?'' were answered. Surface areas, determined from krypton gas adsorption, were found to be high, making GLAD promising for applications requiring large and rough surface interfaces. Specifically, peak specific surface areas of 700 +/- 150 m^2g^{-1}, 325 +/- 40 m^2g^{-1}, 50 +/- 6 m^2g^{-1} were measured for silica (SiO_2), titania (TiO_2) and indium tin oxide (ITO), respectively. Broad pore distributions, with peaks in the low mesoporous regime of 2 nm to 5 nm, were also determined. The internal surface area may also be up to three times as high as that of the externally exposed surface. As well, despite the fact that GLAD column broaden as they grow, the surface area increases linearly with film thickness. Focused ion beam milling, with concurrent SEM imaging, was then employed to investigate and reconstruct the three-dimensional structure of GLAD films in the tens of nanometers regime not measurable by krypton gas adsorption porosimetry. The measured growth scaling trends agreed with previous findings, but were determined using only one sample, instead of multiple samples of increasing thickness. Mean column diameters, center-to-center spacings, void spacings, and column densities were found to scale with thickness as w = (9.4 +/- 3.0) t^{0.35 +/- 0.09} nm, c = (24.8 +/- 5.2) t^{0.31 +/- 0.08} nm, v = (15.2 +/- 3.8) t^{0.25 +/- 0.06} nm, and d = (3400 +/- 2500) t^{-0.65 +/- 0.15} columns um^{-2}, respectively. Finally, spatially graded nanostructures were demonstrated by extending the GLAD technique to include macroscopic shadowing. Optically transparent, graded thickness and pitch helical films were fabricated with polarization selectivity over a spatial range of 30 mm, concurrent with 70 nm spectral tunability. These structures will be useful for tunable frequency photonic devices. / Micro-Electrical-Mechanical Systems (MEMS) and Nanosystems

This thesis investigates technologies directed towards developing photonic crystal display devices. A switching technology based on dye electrophoretic motion within a 1D porous photonic crystal was developed. Dissociated absorbing dye species were moved through the assembled device and reflectance was controllably altered by up to 0.4. Refinement of fabrication techniques yielded a slow switching device, whose time-resolved reflectance data was analyzed. A wavelength dependence of the device switching speed was observed. This phenomenon was described by modelling where bandgap effects match observation. These devices may be improved by employing a 3D photonic crystal. We developed a nanoimprint lithography technique for seeding films deposited by GLAD for the fabrication of 3D square spiral photonic crystals. Parameters for patterning a precisely defined mould pattern using electron beam lithography were established. A large area diamond:1 square spiral photonic crystal was fabricated on the nanoimprinted seeds, and it exhibited a visible wavelength bandgap. / Micro-Electro-Mechanical Systems (MEMS) and Nanosystems

The present work analyses the physicochemical phenomena responsible for the microstructure of Pd/SiO2 xerogel catalysts and of metal-free hybrid SiO2 xerogels synthesized by sol-gel process. The samples are synthesized by co-polymerizing tetraethoxysilane (TEOS) with 3-aminopropyltriethoxysilane or 3-(2-aminoethylamino)propyltrimethoxysilane in ethanol, the latter co-reactant possibly forming a complex with palladium. The analysis is conducted by following in situ the formation of the gels' nanostructure by Small-Angle X-ray Scattering (SAXS), by characterizing the microstructure of the final gels by beam-bending, and by analyzing the microstructure of the xerogels after desiccation, most notably by electron tomography. The in situ SAXS analysis shows that the nanometer structure of the gels forms via a reaction-induced phase separation. The microstructure of the hybrid xerogels is hierarchical, as assessed by electron microscopy, nitrogen adsorption and SAXS. Its structure is that of a microcellular foam at large scale, with pores a few hundred nanometers across, supported by elongated filaments, a few ten nanometers wide, each filament being made up by smaller structures, a few nanometers wide. The characteristics of the various structural levels depend on the nature and concentration of the co-reactant used. In the case of xerogel catalysts, electron tomography shows that Pd nanoparticles are regularly dispersed inside the silica, with distances between them comparable to the thickness of the skeleton. On the basis of the time-resolved SAXS and of the characterization of the xerogels, it is argued that a double phase separation process is responsible for the structuring of the gels, with a primary phase separation leading to the microcellular foam morphology, and a secondary phase separation being responsible for the substructure of the filaments. The large scale structure of the gels themselves, before desiccation, is analyzed by beam bending. This enables one to estimate the mechanical properties of the gels as well as the size of their largest pores. The microstructure of aerogels obtained by supercritical drying of the samples is also investigated. The comparison of the characterization data show that the nature and concentration of the co-reactant controls the amount of shrinkage that the gels undergo during desiccation, at the macroscopic scale as well as at the scale of the filaments.

Both blind and sighted persons may use echoes for detecting objects. The effect of object size on echolocation was tested in a listening experiment with 15 sighted participants. Noise burst of 500-ms were generated and recorded in an ordinary room, with and without a reflecting object. The diameter of the reflecting object was 0.25 or 0.50 m, and it was located at a distance of 0.5, 1, 2, 3 m from the microphones. Pairs of sounds, one with and one without the object, were presented to the listeners. Their task was to decide which of the two sounds that were recorded with the reflecting object. The results showed that it was harder to detect the 0.25 than the 0.5 m object, and that performance generally decreased with distance. The auditory angle, which is a function of the size to distance ratio, was found to predict detection performance fairly well. Sighted

Rubbing alignment is widely used in display industry, Rubbing cause anisotropy in rubbed polyimide thin film influence the alignment of Liquid Crystal. The major part of this article is to analyze surface optical anisotropy of rubbed polyimide thin film. RAS signals and surface free energies of rubbed polyimide thin film with different rubbing strength are measured, and relationship between anisotropy of surface and rubbing strength is discussed. The mechanism of alignment can be understood by this work. Reflection Anisotropy Spectroscopy (RAS) has been used in Semiconductor as a tool to monitor crystal growth for many years. RAS is a non-contact and non-destructive measurement method. It only measures the difference of two orthogonal complex reflection signals and optical anisotropy of surface. It¡¦s very sensitive to the anisotropy of surface. In the current studies, RAS has been used to detect surface anisotropy of rubbed polymer. We measured the surface free energy of the rubbed polyimide thin films. It has been found that surface free energy is of anisotropy due to the application of mechanical rubbing to the polymer surface. Pretilt angle influences the alignment of liquid crystals. The molecule orientation of PI surface and anisotropy of rubbed PI surface effect pretilt angle¡CPretilt angles measured by pretilt angle measurement system compare with RAS signals. RAS signals, anisotropy of surface free energies, and pretilt angles are increasing with increasing rubbing strength.