Mobile devices are becoming more prevalent and complex. As a result, the wireless communication aspect of these devices is becoming increasingly significant. At the same time, video demands in terms of availability and quality are also on the uprise. High definition (HD) video is the standard of choice for meeting today's video demands. However, HD video is characterized by high data rates. Therefore, there is heightened interest in the 60-GHz spectrum as it is suitable for streaming uncompressed HD video. On the other hand, 802.11 wireless technology, compared to 60-GHz, is much more established and widely available and able to cater to a wide variety of devices. HD video compressed using H.264 can be wirelessly streamed via 802.11 wireless networks. However, such wireless networks are prone to packet losses, which result in degraded perceptual quality of video. It is thus important to perform error concealment in order to improve the visual quality of degraded video. Among the key techniques in performing error concealment on video compressed with H.264 is spatial motion vector recovery. This paper proposes a new spatial motion vector recovery technique (MI-WAM) that takes advantage of properly decoded motion vectors. MI-WAM and pre-existing MV recovery techniques are used to provide different corresponding macroblock candidates that compete for the best concealment of each lost macroblock in what will be referred to as competitive motion vector recovery (CMVR). / Graduation date: 2012

An epicyclic-type automatic transmission is a device which is connected from the engine to the driven wheels. A Lepelletier automatic transmission consists of a two-DOF epicyclic gear mechanism and a fundamental geared entity, which can provide more speed ratios. For the development of automatic transmission with eight or more speed ratios, an efficient design methodology is urgently needed and still not available. Therefore, the purpose of this article is to develop a systematic method for the design of Lepelletier automatic transmission. First, the features and requirements of the Lepelletier automatic transmissions are investigated and the corresponding design requirements are induced. Next, the theory of the analysis of speed ratios for Lepelletier automatic transmission is derived based on the concept of lever analogy. Then, the design theory of Lepelletier automatic transmission is developed based on the analysis theory. Finally, the complete atlas of six-speed and eight-speed Lepelletier automatic transmissions can be systematically synthesized from the data of three given speed ratios. In this article, the innovative and patentable six-speed and eight-speed Lepelletier automatic transmissions with the simplest structure have been. This proposed design method can also be applied to the development and design of ten-speed Lepelletier automatic transmissions.

No description available.

Phase-transformation-induced microstructures, including twin domains, anti-phase domains and inversion domains have been analyzed using the scanning and transmission electron microscopy for BaTiO3, BaCeO3 and CaTiO3 of the perovskite structure. Differential etching rate was taken to identify the ferroelectric domains in tetragonal (t-) BaTiO3. Space group Pbnm (No. 62) usually adopted for the orthorhombic crystals by materials scientists is assumed throughout this research to avoid confusion of the plane and direction indices. Traditional contrast analysis was adopted for determining dislocation Burgers vectors (b) and fault vectors (R) in deformed and phase-transformed perovskites, synthetic ceramics (BaTiO3, BaCeO3 and CaTiO3) as well as natural minerals (CaTiO3), polycrystalline (BaTiO3, BaCeO3 and CaTiO3) as well as single crystal (CaTiO3). Atomic images for the structures of twin boundaries and anti-phase boundaries were taken by high resolution technique and image contrast enhancement was performed using fast Fourier transform. Failure of Friedel¡¦s law is adopted for determining if the crystal belongs to non-centrosymmetric point groups. Whether the twins are £_-, £\- or £k-type (i.e. anti-phase domain boundaries) is analysed from the contrast of extreme fringe patterns. Tilting experiments were performed on selected area diffraction patterns containing un-split row of reflections to ensure that the twin boundaries are the reflection or rotation type. Transformation twinning in all perovskites studied here follows the prediction by the relation of point group symmetries between the high- and low-symmetry phases, assuming continuous, diffusionless, second-order transitions that obey the restrictions imposed by the Landau theory of phase transition. Although such predictions of transformation-induced twinning are only permitted when crystallographic group-subgroup relationship exists and structural coherence retains between the high- and low-symmetry phases, experimental observations for r (rhombohedral) ¡÷ o-BaCeO3 and t ¡÷ o in CaTiO3 that are not related by group-subgroup, c (cubic) ¡÷ t (tetragonal) in CaTiO3 and and c (cubic) ¡÷ t (tetragonal) in BaTiO3 that are related by group-subgroup, are all consistent with the predictions from loss of point group symmetry elements and change of unit cell volume. In order that the Landau theory is conformed, however, an intermediate phase of either the lowest common supergroup (cubic Pm m) or highest common subgroup (monoclinic C2/c), with phase transition experiencing multistage pathways suggested by Christy and assumption of non-disruption conditions proposed by Guymont, was identified to bridge between two structures, such as rhombohedral and orthorhombic that are not group-subgroup related. Both the 90o and 180o ferroelectric twin domains in t-BaTiO3 are the reflection type and have been identified in pressureless-sintered ceramics. Further, fault vectors (R = £`<110]) for such domain boundaries were determined, boundary planes of {110) for the former, {100) and {220) for the latter deduced accordingly. The polar c-direction between adjacent domains was determined by differential etching rate across domain boundaries, convergent beam electron diffraction was also adopted for identification and confirmation of the c-axis for two types of domains in t-BaTiO3. Plastic deformation resulting from the thermodynamic driving force for sintering (?p) intensified by a multiplication factor £p) was evidenced microstructurally from analysing dislocations in pressureless-sintered BaTiO3 where a Frank-Read source was observed. Slip systems are activated for the effective stress acting on the slip plane along the slip direction has exceeded the critical value of resolved shear stress (£nCRSS) and yielding occurs. It has contributed to densification, i.e. the overall system shrinkage of a green powder compact, although if such contribution is at all significant requires studies of sintering kinetics to ascertain. Dislocation dissociation into the scallop-shaped half partials according to the following reactions is determined from analysing corresponding Burgers vectors. [010] + [001] ¡÷ [011] [001] + [10 ] ¡÷ [100] [001] + [110] ¡÷ [111] Both transformation twins lying in {110) and {112) and anti-phase domain boundaries with R = 1/2<111> are detected in o-BaCeO3. For orthorhombic (o-) BaCeO3, fault vectors of the latter R = 1/2<111> determined by contrast analysis was confirmed by high-resolution imaging, but on the contrary, fault vectors the former R = £`<110] and £`<021], respectively, could not be determined from such images. Utilizing the technique of large-angle convergent beam electron diffraction, such fault vectors and dislocation Burgers vectors determined by traditional contrast analysis have been confirmed. Both twinning and dislocations were observed in hot-pressed CaTiO3 prepared in a multi-anvil apparatus. Such twins are deformation twins since hot-pressing was conducted in the orthorhombic stable phase field at 1000oC under 8 GPa. Since fault vectors R = £`<110] determined for {112) and {110) twins are different from the transformation-induced twins in o-CaTiO3, R = £`<021] determined for the {112) twinning in natural perovskite may serve as a diagnostic feature for the deformation twins. Plastic deformation in hot-pressured sample was contributed by both slip and twinning. Slip occurred via slip systems with dislocations of b = [110] gliding in (110) is therefore {110}o <1 0>o (equivalent to {100}pc <001>pc, where pc for pseudo-cubic) often found in perovskites deformed at high temperatures. Another set of dislocations with b = [001] in screw orientation was also determined. APB with R = 1/2<111> detected in natural minerals suggests that the phase transition sequence in CaTiO3 is better described by: (c) ¡÷ t (I4/mcm) ¡÷ o (Pbnm) and such APB are generated from loss of the lattice point at I-centre (1/2,1/2,1/2) in the absence of a second orthorhombic Cmcm between t-I4/mcm and o-Pbnm reported before from neutron and X-ray powder diffraction studies.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 83-88).

Thesis (Ph. D.)--University of Missouri--Columbia, 2002. / Typescript. Vita. Includes bibliographical references (leaves 121-148). Also issued on the Internet.

No description available.

The thesis follows the development of an advanced solar photovoltaic power conversion system from first principles. It is divided into five parts. The first section shows the development of a circuit-based simulation model of a photovoltaic (PV) cell within the 'SABER' simulator environment. Although simulation models for photovoltaic cells are available these are usually application specific, mathematically intensive and not suited to the development of power electronics. The model derived within the thesis is a circuit-based model that makes use of a series of current/voltage data sets taken from an actual cell in order to define the relationships between the cell double-exponential model parameters and the environmental parameters of temperature and irradiance. Resulting expressions define a 'black box' model, and the power electronics designer may simply specify values of temperature and irradiance to the model, and the simulated electrical connections to the cell provide the appropriate I/V characteristic. The second section deals with the development of a simulation model of an advanced PVaware DC-DC converter system. This differs from the conventional in that by using an embedded maximum power tracking system within a conventional linear feedback control arrangement it addresses the problem of loads which may not require the level of power available at the maximum power point, but is also able to drive loads which consistently require a maximum power feed such as a grid-coupled inverter. The third section details a low-power implementation of the above system in hardware. This shows the viability of the new, fast embedded maximum power tracking system and also the advantages of the system in terms of speed and response time over conventional systems. The fourth section builds upon the simulation model developed in the second section by adding an inverter allowing AC loads (including a utility) to be driven. The complete system is simulated and a set of results obtained showing that the system is a usable one. The final section describes the construction and analysis of a complete system in hardware (c. 500W) and identifies the suitability of the system to appropriate applications.

No description available.

Thesis (M.S.)--Rochester Institute of Technology, (1989). / Includes bibliographical references (leaves 170-171).