Production of hydrogen-rich synthetic gas from low-grade coals by microwave steam-plasmas

Indonesian brown-coal with high ash-content is gasified by two microwave steam-plasmas heating up the gas temperature in a reaction chamber of 1145 l in a swirl-type gasifier for production of hydrogen-rich synthetic gas. With additional heating of synthetic gas by a partial oxidation of coal, the inner temperature of the gasifier can reach to 1700 °C. The carbon conversion rate at the chamber temperature of 1640 °C is almost 100 percent, ensuring a complete gasification of carbons in a low-grade coal. The cold gas efficiency of the hydrogen-rich synthetic gas is 84%, very high in a relatively-small gasifier like the experiment here. The total calorific value of the synthetic gas is 500 kW.     

Dynamics,NOx and flashback characteristics of confined premixed hydrogen-enriched methane flames

The operating regime of a gas turbine combustor is highly sensitive to fuel composition changes. In particular, the addition of hydrogen, a major constituent of syngas, has a major effect on flame behavior due to the higher burning rates associated with hydrogen. A laboratory scale premixed test rig is constructed in order to study such effects. The fuel composition is incremented with increasing hydrogen starting from 100% methane. It is observed that increased RMS pressure levels and higher susceptibility to flashback occur with increasing hydrogen volume fraction. Furthermore, hydrogen enrichment can cause an abrupt change in the dominant acoustic mode. Measurements are reported of real-time heat release, emissions and flashback. Particular emphasis is put on understanding the relationship between the thermo-acoustic induced pressure oscillations and flashback.     

Global optimal attitude estimation using uncertainty ellipsoids

A deterministic attitude estimation problem for a rigid body in a potential field, with bounded attitude and angular velocity measurement errors is considered. An attitude estimation algorithm that globally minimizes the attitude estimation error is obtained. Assuming that the initial attitude, the initial angular velocity and measurement noise lie within given ellipsoidal bounds, an uncertainty ellipsoid that bounds the attitude and the angular velocity of the rigid body is obtained. The center of the uncertainty ellipsoid provides point estimates, and the size of the uncertainty ellipsoid measures the accuracy of the estimates. The point estimates and the uncertainty ellipsoids are propagated using a Lie group variational integrator and its linearization, respectively. The attitude and angular velocity estimates are optimal in the sense that the sizes of the uncertainty ellipsoids are minimized.     

Semianalytical approach of asynchronous MC-CDMA systems with a cyclic prefix

In this letter, asynchronous multicarrier-code division multiple access (MC-CDMA) systems with a cyclic prefix (CP) are analyzed over frequency-selective multipath fading channels, and the average bit error rate is evaluated. The derived results show that a CP is required for MC-CDMA systems in order to mitigate intersymbol interference (ISI) and fully obtain the achievable path diversity as the frequency diversity.     

Removals of hydrogen peroxide and hydroxyl radical by thiol-specific antioxidant protein as a possible role in vivo

Thiol-specific antioxidant protein (Protector Protein; PRP) from Saccharomyces cerevisiae was found to remove hydrogen peroxide and hydroxyl radical in the presence of dithiothreitol (DTT). Without DTT as a reducing equivalent, the antioxidant protein did not show the activities for destroying hydrogen peroxide and hydroxyl radical. N-ethylmaleimide (NEM) was observed to prevent the PRP from both removing hydrogen peroxide and protecting the cleavage of DNA. These observations suggest that the sulfhydryl of cysteine in PRP could function as a strong nucleophile to attack and destroy H2O2 and .OH.     

The abnormality in gate oxide failure induced by stress-enhanced diffusion of polycrystalline silicon

An abnormal gate oxide failure was found in DRAM using deep submicron technology. Contrary to the general dielectric extrinsic breakdown, the degradation of gate oxide integrity was shown only in the gate lines of a small dimension, not in those of a large dimension. This abnormal oxide breakdown is due to the voids in the polycrystalline silicon, which are at the center of gate line with a small dimension. These voids are formed by both chemical potential difference and stress enhanced diffusion of polycrystalline silicon. The suppression method of these voids using sufficient source of polycrystalline silicon is proposed.     

Accelerated durability test of DMFC electrodes by electrochemical potential cycling

Durability of direct methanol fuel cell electrodes was evaluated by electrochemical potential cycling and we observed the degradation phenomena during the performance decay. An individual potential measurement of anode and cathode with built-in reversible hydrogen electrode revealed that the anode and cathode performance contributions are almost of the same order of magnitude to the entire performance loss, although the anode degradation is relatively bigger, due to the dominating effect of ruthenium dissolution, corresponding loss of electrocatalytic activity. On the contrary, it was apparent that the electrochemical active surface area of Pt cathode decreased significantly with potential cycling under methanol crossover condition, which is not clearly reflected on the performance loss due to the initial decrease of interfacial resistance between membrane and cathode catalyst layer. Impedance studies could reinforce the current–voltage polarization by more comprehensive information.     

Synthesis of titanium oxide thin films containing antibacterial silver nanoparticles by a reactive magnetron co-sputtering system for application in biomedical implants

Titanium oxide thin films containing silver (Ag) nanoparticles were synthesized on commercially pure titanium (cp-Ti) substrates using a reactive magnetron co-sputtering method. The goal was to maximize bactericidal activity along with sustained biocompatibility. Furthermore, this study examined the correlation between Ag nanoparticle dispersion in the films and the antibacterial efficacy of the Ag ions released from the films. The results showed that there might be two factors affecting the inhibition of bacterial attachment to the surface of the specimens: surface morphology and Ag ion release. MTT assay results demonstrated that there was no cytotoxicity on fibroblast cells in any group. Overall, the magnetron sputtered Ag nanoparticle-containing titanium oxide coatings in this study can be used as an efficient antibacterial layer with sustained biocompatibility.     

Enhancement of CO Tolerance on Electrodeposited Pt Anode for Micro‐PEM Fuel Cells

Electrodeposited and sprayed Pt anode catalysts were electrochemically characterised by CO stripping voltammetry as well as their activity to CO tolerance in micro‐PEMFCs was demonstrated using polarisation measurements. While the onset and peak potentials of CO oxidation on the sprayed Pt/C varied with the CO coverage, these were lower (∼50 mV) with the electrodeposited Pt anode. This difference is attributed to the varying properties of the Pt–OH on either rough or smooth surface mainly created from different sizes of Pt particles. In fuel cell performance test, the electrodeposited Pt anode showed maximum power density of 360 mW cm^–2 and it was markedly (∼110 mW cm^–2) higher than the sprayed Pt/C anode. The enhanced activity of the electrodeposited Pt anode is also reflected by the fact that the entire amount of adsorbed CO becomes almost desorbed during the first three polarisation scans, while with the Pt/C anode at least five cycles are required.