DIRECT ADAPTIVE CONTROL FOR NONLINEAR MATRIX SECOND‐ORDER SYSTEMS WITH TIME‐VARYING AND SIGN‐INDEFINITE DAMPING AND STIFFNESS OPERATORS

A direct adaptive control framework for a class of nonlinear matrix second‐order systems with time‐varying and sign‐indefinite damping and stiffness operators is developed. The proposed framework guarantees global asymptotic stability of the closed‐loop system states associated with the plant dynamics without requiring any knowledge of the system nonlinearities other than the assumption that they are continuous and bounded. The proposed adaptive control approach is used to design adaptive controllers for suppressing thermoacoustic oscillations in combustion chambers.     

Non-hookean stress-strain response and changes in crystallite orientation of carbon fibres

The non-hookean stress-strain response of carbon fibres was investigated in relation to changes in crystallite orientation with tensile stress. Various one-dimensional array models and a mosaic model were examined. Amongst these models, only the mosaic model in which the stress of the crystallites can be transmitted in both the transverse and the axial directions showed any quantitative agreement with the measured increases in the tensile modulus and the crystallite orientation with tensile stress. This suggests that deformation of the crystallites is constrained with increasing tensile stress. It was also found that the ratio of the tensile stress of the fibre to that of the crystallites is close to the crystallite volume fraction rather than the ratio of the fibre density to the crystallite density.     

Effect of immunosuppression on composition of quasispecies population of hepatitis C virus in patients with chronic hepatitis C coinfected with human immunodeficiency virus

BACKGROUND/AIMS: To study the effects of the immunosuppression caused by the reduction of CD4 activity on the composition of hepatitis C virus (HCV) populations, we analyzed the number of HCV quasispecies clones and the nucleotide diversity of the hypervariable region 1 (HVR1) of HCV in 37 patients with hemophilia with persistent HCV infection, with or without human immunodeficiency virus (HIV). METHODS: The numbers of HCV quasispecies clones were measured by fluorescence single-strand conformation polymorphism analysis. Direct sequencing was used to analyze the degree of diversity of HVR1. We compared these values according to coinfection with HIV, and CD4 counts of patients. RESULTS: There were no differences in either the number of HCV clones or the diversity between patients with and without HIV coinfection. In HIV coinfected patients the diversity decreased in association with the decrease in CD4 count while the number of HCV clones did not. The diversity of HVR1 was 3.64 +/- 5.03% in patients with a CD4 count < 50/microliters and 14.92 +/- 6.03% in patients with a CD4 count > or = 50/microliters; it was significantly lower in the former (p = 0.0002). CONCLUSIONS: A severe reduction in the CD4 count, which is considered to cause a decline in the activity of helper T-lymphocytes, induced changes in the composition of HCV populations; one or a few quasispecies clones are predominant in the HCV population in the serum of individual patients.     

Lithium-doped sulfated-zirconia catalysts for oxidative coupling of methane to give ethylene and ethane

Li-doped sulfated-zirconia catalysts were found to be effective for oxidative coupling of methane (OCM). The catalyst performances depend on the sulfate content and calcination temperature. A maximum C₂ yield is attained over the catalysts, which contain 6 wt.% sulfate and calcined at 923–973 K, being closely related to the preparation conditions of sulfated-ZrO₂ as solid super-acids. When the performances of the Li-doped sulfated-ZrO₂ (Li/SZ) catalysts were tested at 1023 K as a function of reaction time, both the C₂ and CO_x selectivities remained constant over the range of 8 h, but the CH₄ conversion decreased from 17.5% to 11.9%. The nature of Li/SZ catalysts for the OCM was investigated by X-ray diffraction, XPS, and NH₃ and CO₂ TPD measurements. It could be postulated that the sulfated-ZrO₂ surface could play an important role in the formation of a catalytically active structure by Li-doping.     

Outcomes of 50 leukemia patients who received bone marrow transplants from unrelated donors]

In this study, we examined the ability of tumour necrosis factor-alpha (TNF) to stimulate the mitogen-activated protein (MAP) kinase homologues p42/44 MAP kinase, c-Jun NH2-terminal kinase (JNK) and p38 MAP kinase and its effect upon DNA synthesis in primary cultures of bovine aortic endothelial cells (BAECs). TNF strongly stimulated p38 MAP kinase and JNK activity in both a time- and concentration-dependent manner. By contrast, TNF was a very poor activator of p42/44 MAP kinase relative to the known activator of p42/44 MAP kinase in endothelial cells, adenosine triphosphate (ATP). TNF-stimulated activation of p38 MAP kinase, and MAPKAP kinase-2, a known downstream target of p38 MAP kinase, was strongly inhibited by pre-incubation with the p38 MAP kinase inhibitor SB203580, whereas the minor activation of p42/44 MAP kinase was abolished by pre-incubation of the cell with the novel MAP kinase kinase 1 inhibitor PD098059. Addition of TNF resulted in a 50-60% decrease in DNA synthesis in BAECs. Pre-incubation with PD098059 or co-incubation with ATP failed to modify the inhibitory effect of TNF upon DNA synthesis. SB203580 reduced basal DNA synthesis by approximately 50%; however, if failed to modify the inhibition mediated by TNF. These results indicate that TNF strongly activates both p38 MAP kinase, JNK and, to a minor extent, p42/p44 MAP kinase. It is likely that only one of these kinases, JNK, plays a role in the regulation of DNA synthesis in these cells.     

Breakdown Characteristics of N2O Gas Mixtures for Quasiuniform Electric Field under Lightning Impulse Voltage

From the viewpoint of mitigating global warming by SF₆ gas, this paper discusses breakdown (BD) characteristics of different electronegative gas mixtures with N₂O gas as SF₆ gas substitutes for quasi-uniform electric field under lightning impulse voltage applications. Experimental results revealed the positive synergism in breakdown strength of binary N₂O / CO₂ and ternary N₂O / CO₂ / O₂ gas mixtures, respectively. Furthermore, N₂ gas as a retardant gas was also mixed with the electronegative gas mixtures in order to reduce the electron energy into the effective levels of electron attachment ability by the electronegative gas mixtures. As the result, ternary N₂O / CO₂ / N₂ and quaternary N₂O / CO₂ / O₂ / N₂ gas mixtures could exhibit the significant synergistic effect in breakdown strength. The optimum mixture rate of quaternary N₂O / CO₂ / O₂ / N₂ gas mixtures was consistent with that estimated by assuming the independent contribution of component gases to the improvement of impulse BD characteristics.     

Dynamic breakdown characteristics of liquid helium induced by aquench of superconducting wire and coil

For practical insulation design of superconducting power apparatus, it is necessary to take into account an inherent phenomenon known as quench, the transition from the superconducting to the normal state. We investigated quench-induced dynamic breakdown and prebreakdown characteristics of liquid helium (LHe). Experimental results revealed that the quench of the superconductor drastically reduced the breakdown voltage of LHe in the thermal bubble disturbance. Moreover, dynamic breakdown characteristics in a quasi-uniform field using a superconducting coil were investigated. The results revealed that the breakdown was induced in the quench-initiated region where the largest thermal energy was generated     

DC‐linked hybrid generation system with an energy storage device including photovoltaic generation and gas engine cogeneration for residential houses

For the past few years, hybrid generation systems including solar panel and gas cogeneration have been used for residential houses. Solar panels can generate electronic power at daytime but not at night. But the power consumption of residential houses usually peaks in the evening. The gas engine cogeneration system can generate electronic power without such a restriction, and it also can generate heat power to warm up a house or to produce hot water. In this paper we propose a solar panel and gas engine cogeneration hybrid system with an energy storage device, combined by a DC bus. If a blackout occurs, the system still can supply electronic power for special house loads. We propose a control scheme for the system related to the charging level of the energy storage device and the voltage of the utility grid, which can be applied to both grid‐connected and standalone operation. Finally, we report experiments designed to demonstrate system operation and calculations for loss estimation. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 182(4): 29–46, 2013; Published online in Wiley Online Library ( wileyonlinelibrary.com ).DOI 10.1002/eej.22321     

Simultaneous removal of NO/sub x/, SO/sub x/, and CO/sub 2/ at elevated temperature using a plasma-chemical hybrid process

In previous studies, the authors confirmed that the plasma-chemical combined hybrid process for controlling NO flue gas emission was extremely effective and economical in comparison with the conventional selective catalytic reduction (SCR) system and other technologies. In the present study, we carried out experiments on the simultaneous removal of NO/sub x/ and SO/sub x/ at elevated temperature using the plasma-chemical hybrid process. A series of experiments was performed to quantify all the reaction byproducts such as N/sub 2/O, CO, HNO/sub 2/, HNO/sub 3/, NO/sub 3//sup -/, and SO/sub 4//sup -/ to evaluate the simultaneous NO/sub x/ and SO/sub x/ removal efficiency. The oxidation from NO to NO/sub 2/ without decreasing NO/sub x/ concentration (i.e., minimum reaction byproducts) and with least power consumption is the key for the optimum operation of the plasma reactor. The produced NO/sub 2/ was totally converted to N/sub 2/ and Na/sub 2/SO/sub 4/ with Na/sub 2/SO/sub 3/ or Na/sub 2/S with and without NaOH using the barrier-type packed-bed plasma reactor followed by the packed-column chemical reactor. The NO/sub 2/ reduction was more effective for Na/sub 2/S than Na/sub 2/SO/sub 3/ but produces H/sub 2/S with Na/sub 2/S. For both cases at least five times the stoichiometric amount of chemicals were required for complete NO/sub 2/ reduction. Nearly 100% of NO/sub x/ and SO /sub 2/ and 40% Of CO/sub 2/ simultaneous removal were achieved with less than 5 ppm of N/sub 2/O and CO. The operating cost was less than 1/4 the SCR process. The additional SO/sub 2/ treatment system can be eliminated.