Hydrokinetic Energy Harnessing by Enhancement of Flow Induced Motion using Passive Turbulence Control.

Horizontal Marine Hydro-Kinetic (MHK) energy in the form of currents/tides/rivers is worldwide available. The vast majority flows at speeds slower than 3 knots while tur-bines require an average of 5-7knots to be financially viable. The VIVACE Converter (Vortex Induced Vibration for Aquatic Clean Energy) is an innovative energy converter, which is highly scalable and can thus extract energy from even slow flows using the po-tentially disastrous phenomenon of Vortex Induced Vibrations (VIV) or galloping. Due to the self-limiting nature of VIV, the range of synchronization and the amplitude of oscillation restrict the amount of energy generated. The goal of this thesis is to enable VIVACE to attain higher power generation with higher efficiency using high damping required for energy harnessing. Passive Turbulence Control (PTC) utilizing roughness strips is developed and tested experimentally to en-hance Flow Induced Motion (FIM). Experiments are conducted for 4×104<Re<1.2×105 using PTC on a circular cylinder undergoing VIV and galloping. PTC is applied as straight roughness strips at specific circumferential locations on a circular cylinder surface to alter its FIM in a steady flow. Effectively, geometry is changed to non-circular, which results in a flow incidence angle, leading to high-amplitude oscillations known as galloping. All model tests were conducted with broad-field laser visualization at 4×104<Re<1.2×105 in the Marine Renewable Energy Laboratory of the University of Michigan. The following observations and conclusions are made: (1) PTC coverage of 16° is effective in the range of 10°-64°. (2) PTC reduces VIV amplitudes, but extends the VIV synchronization range followed by high-amplitude galloping. (3) Galloping initiates at a critical reduced velocity U*gallop, manifests to fully-developed galloping with no re-duced velocity upper-end reached. (4) U*gallop is found to depend primarily on the PTC location. (5) Wake structures change dramatically reaching up to ten vortices shed per cycle of galloping oscillation. (6) The higher the surface roughness, the higher is the maximum amplitude of galloping oscillation within the tested roughness range. (7) Two important cross-sectional geometry parameters have been identified and can be used to predict the onset of galloping of a circular cylinder with PTC.Ph.D.Naval Architecture & Marine EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/78766/1/changjim_1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/78766/2/changjim_2.pd

Hafnium oxide-based ferroelectric thin-film transistor with a-InGaZnO channel fabricated at temperatures \u3c= 350°C

HfO2-based ferroelectric materials integrated with oxide-based thin-film transistors have been considered as potential candidates for back-end-of-line compatible ferroelectric field-effect transistors, which can be vertically stacked on silicon CMOS circuits to realize high-density neural network applications. However, the formation of ferroelectric orthorhombic phase in HfO2-based materials usually requires an annealing temperature of 400°C or higher. In this work, ferroelectric thin-film transistors (Fe-TFTs) were developed by monolithically integrating HfZrO2 (HZO) ferroelectric capacitors with amorphous indium-gallium-zinc oxide (a-IGZO) TFTs at a maximum processing temperature of 350°C on a glass substrate. A butterfly-shaped C-V curve was clearly observed in the low-temperature annealed metal-HZO-metal capacitor, indicating the formation of ferroelectricity in the HZO layer, as shown in Fig. 1. The positive and negative coercive voltages were 3 V and -2.4 V, respectively. The dielectric constant was 20.65. The field-effect mobility, threshold voltage, subthreshold swing and on/off current ratio of the a-IGZO TFT extracted from the transfer characteristics shown in Fig. 2 were 6.15 cm2V-1s-1, 1.5 V, 0.1 V/dec and 4.3´107, respectively. Fig. 3 shows the transfer hysteresis curves of the low-temperature Fe-TFTs in a metal-ferroelectric-metal-insulator-semiconductor configuration. The Fe-TFTs exhibited large hysteresis memory windows of 2.8 V and 3.8 V when the area ratios between ferroelectric capacitors and gate insulators (AFE / ADE) were 1/8 and 1/12, respectively. The result shows a great potential for back-end-of-line compatible memory applications. Please click Download on the upper right corner to see the full abstract

The Aharonov Casher phase of a bipartite entanglement pair traversing a quantum square ring

We propose in this article a quantum square ring that conveniently generates, annihilates and distills the Aharonov Casher phase with the aid of entanglement. The non-Abelian phase is carried by a pair of spin-entangled particles traversing the square ring. At maximal entanglement, dynamic phases are eliminated from the ring and geometric phases are generated in discrete values. By contrast, at partial to no entanglement, both geometric and dynamic phases take on discrete or locally continuous values depending only on the wavelength and the ring size. We have shown that entanglement in a non-Abelian system could greatly simplify future experimental efforts revolving around the studies of geometric phases.Comment: 7 pages, 5 figures, 1 tabl

Increased ATP generation in the host cell is required for efficient vaccinia virus production

To search for cellular genes up-regulated by vaccinia virus (VV) infection, differential display-reverse transcription-polymerase chain reaction (ddRT-PCR) assays were used to examine the expression of mRNAs from mock-infected and VV-infected HeLa cells. Two mitochondrial genes for proteins that are part of the electron transport chain that generates ATP, ND4 and CO II, were up-regulated after VV infection. Up-regulation of ND4 level by VV infection was confirmed by Western blotting analysis. Up-regulation of ND4 was reduced by the MAPK inhibitor, apigenin, which has been demonstrated elsewhere to inhibit VV replication. The induction of ND4 expression occurred after viral DNA replication since ara C, an inhibitor of poxviral DNA replication, could block this induction. ATP production was increased in the host cells after VV infection. Moreover, 4.5 μM oligomycin, an inhibitor of ATP production, reduced the ATP level 13 hr after virus infection to that of mock-infected cells and inhibited viral protein expression and virus production, suggesting that increased ATP production is required for efficient VV production. Our results further suggest that induction of ND4 expression is through a Bcl-2 independent pathway

Stateless Two-Stage Multiple Criteria Scheduling in Nuclear Medicine

Examination in nuclear medicine exhibits scheduling difficulties due to its intricate clinical issues, such as varied radiopharmaceuticals for different diseases, machine preparation and length of scan, and patients’ and hospital’s criteria and/or limitations. Many scheduling methods exist but are limited for nuclear medicine. In this paper, we present stateless two-stage scheduling to cope with multiple criteria decision making. The first stage mostly deals with patients’ conditions. The second stage concerns more the clinical condition and its correlations with patients’ preference which presents more complicated intertwined configurations. A greedy algorithm is proposed in the second stage to determine the (time slot and patient) pair in linear time. The result shows practical and efficient scheduling for nuclear medicine