Engineering topics
Liu, S
Publications and source records attributed to Liu, S.
Insights into Mechanism of Glucokinase Activation: Observation of Multiple Distinct Protein Conformations
Abstract not provided
Dense PLZTfilms grown on nickel substrates by PVP modified sol-gel method.
Abstract not provided
OBSERVATION OF HIGH-SPEED OUTFLOWS IN CORONAL LOOPS ASSOCIATED WITH PHOTOSPHERIC MAGNETIC FIELD EVOLUTION
Using SDO/AIA instruments, we provide an EUV observation of two adjacent loop strands (Loops 1 and 2) with one side of their footpoints rooted in the boundaries of active region (AR) NOAA 11158 and the other side in the quiet-Sun regions. The AR footpoints of Loop 1 were located in monopolar magnetic areas and those of Loop 2 in mixed polar areas (SDO/HMI magnetograms). There were no apparent outflows found in Loop 1 in 10 hr of observations, whereas in Loop 2, the outflows were detected throughout the whole observation with an average speed of 120-150 km s{sup -1}. We find clear evidence of magnetic reconnections occurring in the AR footpoints of Loop 2 (the opposite magnetic polarities came close and then a part of them disappeared) and magnetic flux dispersal in the quiet-Sun footpoints (a patch of positive polarities decayed with time). Furthermore, with Hinode/SOT observations, there were no significant Ca II H brightenings detected at the loop footpoints of Loop 2 at the chromospheric heights in response to those of the AIA 171 A and 304 A channels when four strong outflow events took place in the loops, which seem to differ from the conclusions of previous studies. In other studies, the rapid coronal outflows along the coronal loops were found to originate from the chromosphere through transient events (e.g., type II spicules).
Microstructure and electrical properties of LaNiO{sub 3} thin films by RF sputtering for the growth of (Pb,La)(Zr,Ti)O{sub 3} films on silicon and nickel substrates
Conductive LaNiO{sub 3} (LNO) thin films were deposited on Si substrates by RF sputtering at room temperature to 600 Degree-Sign C. X-ray diffraction of the LNO films showed that preferred orientation varied from (100) below 500 Degree-Sign C to (110) at 600 Degree-Sign C at deposition temperature of 200-600 Degree-Sign C. The room temperature resistivity was 2250-3400 {mu}{Omega}-cm at the range of 200 Degree-Sign C {approx}500 Degree-Sign C. The LNO films, deposited at room temperature, were postannealed in air from 500 to 800 Degree-Sign C, and the resistivity value was 280 {mu}{Omega}-cm at a postannealing temperature of 600 Degree-Sign C. Subsequently, sol-gel derived (Pb,La)(Zr,Ti)O{sub 3} thin films were deposited on LNO-buffered nickel substrates and characterized, the results were compared to those of the same films on silicon substrates. The comparison demonstrated that the performance characteristics of the LNO-buffered nickel foils are similar to those of LNO-buffered silicon substrates. Thus, LNO films prepared by the sputtering method can act as an effective barrier layer on nickel substrates for embedded microelectronic devices.
North American Carbon Project (NACP) Regional Interim Synthesis: Terrestrial Biospheric Model Intercomparison
Understanding of carbon exchange between terrestrial ecosystems and the atmosphere can be improved through direct observations and experiments, as well as through modeling activities. Terrestrial biosphere models (TBMs) have become an integral tool for extrapolating local observations and understanding to much larger terrestrial regions. Although models vary in their specific goals and approaches, their central role within carbon cycle science is to provide a better understanding of the mechanisms currently controlling carbon exchange. Recently, the North American Carbon Program (NACP) organized several interim-synthesis activities to evaluate and inter-compare models and observations at local to continental scales for the years 2000 to 2005. Here, we compare the results from the TBMs collected as part of the regional and continental interim-synthesis (RCIS) activities. The primary objective of this work is to synthesize and compare the 19 participating TBMs to assess current understanding of the terrestrial carbon cycle in North America.
Extraction of Normal Electron Self-energy and Pairing Self-energy in the Superconducting State of the Bi2Sr2CaCu2O8 Superconductor via Laser-based Angle-resolved Photoemission
N/A
Modified Johnson model for ferroelectric lead lanthanum zirconate titanate at very high fields and below Curie temperature.
A modified Johnson model is proposed to describe the nonlinear field dependence of the dielectric constant ({var_epsilon}-E loop) in ferroelectric materials below the Curie temperature. This model describes the characteristic ferroelectric 'butterfly' shape observed in typical {var_epsilon}-E loops. The predicted nonlinear behavior agreed well with the measured values in both the low- and high-field regions for lead lanthanum zirconate titanate films. The proposed model was also validated at different temperatures below the ferroelectric-to-paraelectric Curie point. The anharmonic coefficient in the model decreased from 6.142 x 10{sup -19} cm{sup 2}/V{sup 2} to 2.039 x 10{sup -19} cm{sup 2}/V{sup 2} when the temperature increased from 25 C to 250 C.
Enhanced dielectric properties of Pb0.92La0.08Zr0.52Ti0.48O3 films with compressive stress
Abstract not provided
Improved properties of barium strontium titanate thin films grown on copper foils by pulsed laser deposition using a self-buffered layer.
Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} (BST) films were deposited by pulsed laser deposition on copper foils with low-temperature self-buffered layers. The deposition conditions included a low oxygen partial pressure and a temperature of 700 C to crystallize the films without the formation of secondary phases and substrate oxidation. The results from x-ray diffraction and scanning electron microscopy indicated that the microstructure of the BST films strongly depended on the growth temperature. The use of the self-buffered layer improved the dielectric properties of the deposited BST films. The leakage current density of the BST films on the copper foil was 4.4 x 10{sup -9} A cm{sup -2} and 3.3 x 10{sup -6} A cm{sup -2} with and without the self-buffered layer, respectively. The ferroelectric hysteresis loop for the BST thin film with buffer layer was slim, in contrast to the distorted loop observed for the film without the buffer layer. The permittivity (7 0 0) and dielectric loss tangent (0.013) of the BST film on the copper foil with self-buffered layer at room temperature were comparable to those of the film on metal and single-crystal substrates.
Dielectric properties and spectroscopy of large-aspect-ratio ferroelectric thin film heterostructures
No abstract prepared.
Feature-Based Statistical Analysis of Combustion Simulation Data
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Airbreathing Laser Propulsion Experiments with 1 {mu}m Terawatt Pharos III Laser: Part 1
This basic research study examines the physics of airbreathing laser propulsion at the extreme flux range of 1-2x10{sup 11} W/cm{sup 2}--within the air breakdown threshold for l {mu}m radiation--using the terawatt PHAROS III neodymium-glass pulsed laser. Six different experimental setups were tested using a 34 mm line focus with 66 {mu}m focal waist, positioned near the flat impulse surface. The first campaign investigated impulse generation with the beam oriented almost normal to the target surface, with energies ranging from 23 to 376 J, and pulses of 5 to 30 ns FWHM. Air breakdown/ plasma dynamics were diagnosed with GOI cameras and color photography. Laser generated impulse was quantified with both vertical pendulums and piezoelectric pressure transducers using the standard performance metric, C{sub M}--the momentum coupling coefficient. Part 1 of this 2-part paper covers Campaign no. 1 results including laser plasma diagnostics, pressure gage and vertical pendulum data.
Airbreathing Laser Propulsion Experiments with 1 {mu}m Terawatt Pharos IIILaser: Part 2
This basic research study examines the physics of airbreathing laser propulsion at the extreme flux range of 1-2x10{sup 11} W/cm{sup 2}--within the air breakdown threshold for l {mu}m radiation--using the terawatt Pharos III neodymium-glass pulsed laser. Six different experimental setups were employed using a 34 mm line focus with 66 {mu}m focal waist, positioned near the flat impulse surface. The 2nd Campaign investigated impulse generation with the laser beam focused at grazing incidence across near horizontal target surfaces, with pulse energies ranging from 55 to 186 J, and pulse-widths of 2 to 30 ns FWHM. Laser generated impulse was measured with a horizontal Plexiglas registered ballistic pendulum equipped with either a steel target insert or 0.5 Tesla permanent magnet (NEIT-40), to quantify changes in the momentum coupling coefficient (C{sub M}). Part 2 of this 2-part paper covers Campaign no. 2 results including C{sub M} performance data, and long exposure color photos of LP plasma phenomena.