Due to the micro-pillar-structured electrodes were made in the gas diffusion layer (GDL) of the proton exchange membrane fuel cell (PEMFC), the cell performance was raised significantly; the study therefore aims to understand whether the same cell performance can be achieved if the micro-pillar-structures were made in the direct methanol fuel cell (DMFC) of the anode. At room temperature and naturally breathed air, the performance of the micro-pillar-structured electrodes was the same as the conventional electrodes. The performance of the electrodes does not rely on the surface area between the micro porous layers and the catalyst. The experimental results inference indicates that no efficiency can be completed. The study then changed the experimental condition, i.e. increased the temperature of the methanol-water solution to 50¢J and reduced the methanol concentrations to 0.5M. The purpose was to carry out the reaction of the surface between the methanol and the catalyst layer. However, the experimental result shows no variation between the micro-pillar- structured electrodes and the conventional electrodes. Because of the test of the current density of the DMFC was carried out in a small power (0~25mW/cm2). The current density of the PEMFC was carried out in a high power (400mW/cm2 ~). The study proposed that the cell operating temperature can be raised and the oxygen can be put in the cathode, the performance of the micro-pillar-structured electrodes can thus be enhanced if the reaction was in a high current density. At the finals, the study tried to compare the efficiency between self-made electrodes and commercial electrodes (E-TEK). The result showed that both max power densities can reach 17mW/cm2 at room temperature and naturally breathed air.

Bismuth layer structure ferroelectrics (BLSFs) have attracted intensive investigation for the potential use in nonvolatile ferroelectric random access memory (NvRAM/FeRAM) and high temperature piezoelectric devices. In this thesis, there are three kinds of Bi-layered structure ferroelectric ceramics materials prepared by solid-state reaction methods. Investigations have been made on the crystal structure, surface morphology, and dielectric properties of these ferroelectric materials. In the chapter3 of this thesis, ferroelectric materials are SrBi2Ta2O9-based ceramics. One of the materials is SrBi2Ta2O9 composition with excess x wt% Bi2O3 (x=0, 2, and 4). Even 1280oC is used as the sintering temperature of stoichiometric SrBi2Ta2O9 composition, the X-ray diffraction patterns will show that the SrBi2Ta2O9 phase is coexisted with the raw material of Ta2O5 and the secondary phases of SrBi2O4 and BiTaO4. For SrBi2Ta2O9 composition with excess 2wt%- or 4wt%-Bi2O3-doped and sintered at 1040oC, the Ta2O5, SrBi2O4, and BiTaO4 phases are eliminated and only the SrBi2Ta2O9 phase is observed in the X-ray diffraction patterns. The other of SrBi2Ta2O9-based ceramics was doped with V2O5. V2O5 is used to substitute Ta2O5 of the SrBi2Ta2O9 ceramics to form SrBi2Ta2-xVxO9 composition, where x=0.1, 0.2, 0.3, and 0.4. For all SrBi2Ta2-xVxO9 composition, the crystal intensities of the (00l) planes (l =6, 8, 10, 12, and 14) increase with the increase of sintering temperature and saturate at 1050oC-sintered ceramics, and the increase in the crystal intensities of the (008) and (0010) planes are more obvious. For the same sintering temperature, the crystal intensities of the (00l) planes increase with the increase of V2O5 content and saturate at SrBi2Ta1.7V0.3O9 ceramics. In the chapter4, ferroelectric materials are SrBi4Ti4O15-based ceramics. One of the materials is (Sr1-xBax)Bi4Ti4O15 (x=0, 005, 0.1, 0.15, and 0.02), and BaO is used to substitute SrO. Dielectric properties were investigated in the temperature of 25oC~ 805oC at 1MHz. It is found that Curie temperatures are shifted to higher temperature as the BaO content increased. For (Sr1-xBax)Bi4Ti4O15 ceramics sintered at 1150oC, the Curie temperature for x=0, 0.05, 0.1, 0.15, and 0.2 are 645oC, 665oC, 705oC, 725oC, and 745oC, respectively. The other is non-stoichiometric compositions SrBi4Ti4O15+x Bi2O3, (x= -0.04, -0.02, 0, 0.02, and 0.04). From the observations of SEM, the SrBi3.92Ti4O14.88 and the SrBi3.96Ti4O14.94 ceramics reveal a two-phased grain growth, the bar-typed and the irregularly disk-typed grains coexist; The other ceramics will reveal the irregularly disk-typed grains. From the X-ray diffraction patterns, Bi2Ti2O7 and SrTiO3 phases are observed in the SrBi3.92Ti4O14.88 and the SrBi3.96Ti4O14.94 ceramics. Except the SrBi3.96Ti4O14.94 ceramics, the other ceramics have revealed an unapparent splitting peak in the (119) plane. In the chapter5, ferroelectric materials are (Na0.5Bi0.5)TiO3-BaTiO3-based ceramics. The 0.95 (Na0.5Bi0.5)TiO3-0.05 BaTiO3 + x wt% Bi2O3 (x= 0, 1, 2, and 3) ceramics were fabricated by two different processes. The first process is that (Na0.5Bi0.5)TiO3 and BaTiO3 composition was calcined at 850oC and 1100oC, respectly, and then the calcined (Na0.5Bi0.5)TiO3 and BaTiO3 powders were mixed in according to 0.95 (Na0.5Bi0.5)TiO3-0.05 BaTiO3 + x wt% Bi2O3 compositions. The second process was that the raw materials were mixed in accordance to the 0.95 (Na0.5Bi0.5)TiO3-0.05 BaTiO3 + x wt% Bi2O3 compositions and then calcined at 900oC. The sintering process was carried out in air for 2h from 1120oC to 1240oC. As the sintering temperatures are higher than 1160oC, the maximum dielectric constants of ceramics made by the second method are higher than those of ceramics by the first method, and the maximum dielectric constant of this ceramics will reveal in the x =1 ceramics. Both ceramics reveal a broaden dielectric constant-temperature curves. The other is (1-x) (Na0.5Bi0.5)TiO3-x BaTiO3 compositions, where x= 0.03, 0.05, and 0.07, formatted by two different methods given above. The dielectric-temperature curves of (1-x) (Na0.5Bi0.5)TiO3-x BaTiO3-based ceramics are almost unchanged as the measured frequency changed from 10 kHz to 1MHz.

Organic light-emitting Diode (OLED) emits light itself. It owns many advantages of optical-electronic characteristics as compared with Thin Films Transistor-Liquid Crystal Display (TFT-LCD). In order to achieve the requirement for full color flat panel display, the three primary colors which are red, green, blue (R,G,B) with high luminance¡Bhigh current efficiency¡Band high color purity are important study of research and development for OLED. In our experiment, the major materials are NPB¡BDPVBi¡BAlq3¡BLiF¡BPBD¡BDCJTB¡FThe materials of NPB¡BDPVBi¡BAlq3,LiF is used as hole transporting layer¡Bblue emission layer¡Belectron transporting layer, and electron injection layer, respectively. PBD is hole-blocking layer and DCJTB is red emission layer which is intended to indirectly demonstrate the hole-blocking effect in the interface between NPB and DPVBi layer. The blue light emission with short wavelength plays an important role in color conversion method (CCM) of full color technology. In the study, we improve and research on color purity of blue OLED by various thicknesses of organic layer. In addition, we research the influence of the device with different thicknesses of PBD layer as hole-blocking layer. In order to improve the color mixing phenomenon, we add extra DPVBi layer to the device with PBD layer. It can improve the blue color purity and obtain narrower full width at half maximum (FWHM).

<p>The object ofthe present work is to experimentally study thecase ofa turbulent boundary layer subjected to an AdversePressure Gradient (APG) with separation and reattachment. Thisconstitutes a good test case for advanced turbulence modeling.The work consists ofde sign of a wind-tunnel setup, developmentofP article Image Velocimetry (PIV) measurements and evaluationtechniques for boundary layer flows, investigations ofs calingofb oundary layers with APG and separation and studies oftheturbulence structure ofthe separating boundary layer withcontrol by means ofs treamwise vortices. The accuracy ofP IV isinvestigated in the near-wall region ofa zero pressure-gradientturbulent boundary layer at high Reynolds number. It is shownthat, by careful design oft he experiment and correctly appliedvalidation criteria, PIV is a serious alternative toconventional techniques for well-resolved accurate turbulencemeasurements. The results from peak-locking simulationsconstitute useful guide-lines for the effect on the turbulencestatistics. Its symptoms are identified and criteria for whenthis needs to be considered are presented. Different velocityscalings are tested against the new data base on a separatingAPG boundary layer. It is shown that a velocity scale relatedto the local pressure gradient gives similarity not only forthe mean velocity but also to some extent for the Reynoldsshear-stress. Another velocity scale, which is claimed to berelated to the maximum Reynolds shear-stress, gives the samedegree of similarity which connects the two scalings. However,profile similarity achieved within an experiment is notuniversal and this flow is obviously governed by parameterswhich are still not accounted for. Turbulent boundary layerseparation control by means ofs treamwise vortices isinvestigated. The instantaneous interaction between thevortices and the boundary layer and the change in the boundarylayer and turbulence structure is presented. The vortices aregrowing with the boundary layer and the maximum vorticity isdecreased as the circulation is conserved. The vortices arenon-stationary and subjected to vortex stretching. Themovements contribute to large levels ofthe Reynolds stresses.Initially non-equidistant vortices become and remainequidistant and are con- fined to the boundary layer. Theamount ofi nitial streamwise circulationwas found to be acrucial parameter for successful separation control whereas thevortex generator position and size is ofseco ndary importance.At symmetry planes the turbulence is relaxed to a nearisotropic state and the turbulence kinetic energy is decreasedcompared to the case without vortices.</p><p><b>Keywords:</b>Turbulence, Boundary layer, Separation,Adverse Pressure Gradient (APG), PIV, control, streamwisevortices, velocity scaling.</p>

Univ., Diss.--Bremen, 2005.

Thesis (M.S.)--Joint Program in Oceanography/ Applied Ocean Science and Engineering, Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution, 2003. / Includes bibliographical references (p. 70-72).

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Supervisor: Noel T. Clemens Vita. Includes bibliographical references. Also available from UMI.

Thesis (M.S. in E.S.M.)--School of Civil and Environmental Engineering, Georgia Institute of Technology, 2004. Directed by Donald R. Webster. / Includes bibliographical references (leaves 118-121).

Thesis (M.S.)--Mississippi State University. Department of Computational Engineering. / Title from title screen. Includes bibliographical references.

Thesis (M. Sc.)--University of Hong Kong, 1963. / Typewritten.