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31.
An experiment to remove re-deposited layers and to release hydrogen using a glow discharge in oxygen (O-GDC) has been performed in the HT-7 superconducting tokamak. In the absence of magnetic fields, the O-GDC wall conditioning had produced rapid, controlled co-deposit removal. Average removal rates, 5.2 × 1022 H-atoms/h, 5.65 × 1021 D-atoms/h and 5.53 × 1022 C-atoms/h, respectively, were obtained during 145 min O-GDC experiment in the pressure range 0.5-1.5 Pa. The corresponding removal rate of co-deposited films was ∼1.19 μm/day (26.5 g/day for carbon) based on an area of 12 m2. Compared to thermo-oxidation and O-ICR experiment, high pressure O-GDC wall conditioning promoted the oxidation and improved the C and D atoms removal. In the O-GDC experiment, the removal rates of H-atoms and D-atoms as H2O, HDO and D2O were higher than that of H2 and D2 by factors of about 20 and 50, respectively. During the 145 min O-GDC experiment, about 14.5% O-atoms were converted into carbon oxides and hydroxides, and about 5.37 × 1022 O-atoms were adsorbed on the walls corresponding to a coverage of 4.5 × 1021 O/m2 on an wall area of 12 m2. In a 100 min helium glow discharge (He-GDC) following the O-GDC experiment, 1.53 × 1022 O-atoms, about 28.5% oxygen retained on the walls, were removed. The removal rate of H-atoms in He-GDC cleaning after O-GDC experiment was lower than that in He-GDC cleaning before O-GDC experiment, which indicates that the O-GDC wall conditioning had effectively reduced hydrogen retention on the walls. 相似文献
32.
Scattering from bandlimited fractal fibers 总被引:2,自引:0,他引:2
The scattering of electromagnetic or optical waves from tenuous dielectric fibers characterized by bandlimited fractal surfaces is considered. The role of several fractal dimensions is noted, and one suitable for this problem is identified. It is found that in the fractal regime, the Rayleigh-Gans differential scattering cross section as a function of the normalized size parameter exhibits a power-law relation reminiscent of that associated with light scattering from fractal clusters and small-angle X-ray and neutron scattering by porous material. This power-law relation is monotonically related to an appropriate fractal dimension and variance of the fiber surface 相似文献
33.
La doping effects on intergrowth Bi2WO6–Bi3TiNbO9 ferroelectric ceramics were studied by X-ray diffraction, electron probe microanalysis and dielectric spectroscopy. It was found that the La3+ distribution, ferroelectric phase transition and dielectric relaxation behavior are apparently affected by La doping. With increasing La3+ content, the site of dopant ion varies, the grain growth of Bi5TiNbWO15 is restrained, the Curie temperature is reduced and broadened. Furthermore, two dielectric relaxation loss peaks were observed both in temperature and frequency spectra. The calculated relaxation parameters revealed the oxygen vacancy related to the relaxation process. 相似文献
34.
M.-F. Foulon T. Crepin X. Melique D. Lippens 《Microwaves, Antennas & Propagation, IET》2007,1(1):23-28
Co-planar strip (CPS) transmission lines, aimed at operating up to sub-millimetre wavelengths, were periodically loaded by lumped capacitances and inductances in series and shunt configuration, respectively. Under this condition, propagation on the line is backward with group and phase velocities of opposite signs. The transmission lines were fabricated onto a quartz substrate by e-beam patterning and thin film deposition, silicon nitride and gold layers, on a deep sub-micron scale (~200 nm). A direct evidence of left-handedness between 160 and 380 GHz was achieved via the tracking of phase advance in a differential phase experiment using electro-optic sampling. The comparison between modelling results by electromagnetic full wave circuit analysis and experiment was performed in the time and frequency domains. It shows a good agreement in the dispersion characteristics and ultra-fast variations in the transmitted signals. At last, we took benefit of a lumped element fitting approach in order to discuss of the frequency capability of this non-resonant approach 相似文献
35.
36.
Ultraviolet (UV) disinfection is becoming increasingly popular as an alternative disinfection technology to chlorination in recent years. In this study, we investigated the photoreactivation of Escherichia coli following medium-pressure (MP) UV disinfection of synthetic water by a bench-scale collimated beam apparatus. The UV doses ranged from 1.6 -19.7 mWs/cm2 and photoreactivation was investigated for 6 hours under fluorescent light. In addition, chloramination was applied after UV disinfection to investigate its ability to control photoreactivation. It was found that photoreactivation occurred for all UV doses tested and the increase in bacteria numbers ranged from 0.04 to 1.35 log10. However, the degree of photoreactivation decreased with increased UV doses. Chloramination experiments revealed that the addition of 0.5 mg/l of monochloramine resulted in suppression of photoreactivation for 1 hour only. An increased monochloramine dose of 1 mg/l was found to prevent photoreactivation for the entire duration of the experiment. The results of this study have shown that photoreactivation occurs even after MP UV disinfection, although it is of a lesser extent at higher UV doses. This study has also established that secondary chloramination can effectively suppress and eliminate photoreactivation with a chloramine dose of 1 mg/l. 相似文献
37.
Lianshan Yan Yeh C. Yang G. Lin L. Chen Z. Shi Y.Q. Willner A.E. Yao X.S. 《Lightwave Technology, Journal of》2003,21(7):1676-1684
We demonstrate the first programmable group-delay module based on polarization switching. With a unique binary tuning mechanism, the device can generate any differential group delay value from -45 to +45 ps with a resolution of 1.40 ps, or any true-time-delay value from 0 to 45 ps with a resolution of 0.7 ps. The delay varying speeds for both applications are under 1 ms and can be as fast as 0.1 ms. We evaluate both the dynamic and static performances of the device while paying special attention to its dynamic figures of merit for polarization-mode dispersion emulation and compensation applications. Our experiment shows that the device exhibits a negligible transient-effect induced power penalty (<0.2 dB) in a 10-Gb/s nonreturn-to-zero system. 相似文献
38.
This paper is concerned with a traction-based Completed Adjoint Double Layer Boundary Element Method to solve for the surface traction of a system of rigid particles embedded in an elastic matrix. The main feature of the method is a single layer representation of the displacement field, which leads to a system of second-kind integral equations for the traction field, the extreme eigenvalue of which could be deflated, allowing iterative solution strategies to be effectively applied. The method is therefore most suitable for large-scale simulations of particulate solids. The method is benchmarked against some known analytic solutions, including the difficult stress singularity problems at sharp edges. The effectiveness of the method in dealing with a large number of inclusions is also demonstrated with an elongational deformation problem involving up to 25 inclusions.Research supported by the Australian Research Council (to NP-T and X-JF) and the National Natural Science Foundation of China (X-JF). 相似文献
39.
Uniformity of bulk density distribution during the die filling process is required to minimize quality problems, such as distortion and cracking, for powder compacts. Understanding the die filling process is necessary in ensuring a uniform powder deposition. The second-generation pressure deposition tester (PDT-II) was used to investigate the deposition process and final pressure distribution of powder filling in toroidal, cylindrical, and E-shaped dies. All tests were conducted using a spray-dried free-flowing granular powder. The results indicated that for toroidal dies: (1) the area around 0° orientation (the leeward end) had the highest pressure values (1186.7 to 2498.0 Pa), with the average pressure values of the remaining area 353.7-648.0 Pa; (2) the pressure distribution was symmetrical about the centerline parallel to the feed shoe movement direction; (3) the highest feed shoe speed (500 mm/s) led to the most nonuniform pressure distribution among the three speeds; (4) higher feed shoe speed did not always result in higher final pressure values; and (5) the right die tended to have higher final pressure values (215.0 to 2498.0 Pa) than the center die (95.4 to 2052.5 Pa). For E-shaped dies: (1) the final pressure values of the middle leg (308.9 to 760.7 Pa) were higher than those of the left and the right legs (148.9 to 530.3 Pa); (2) the area along the backside had the highest final pressure value (1054.6 to 1303.8 Pa); (3) the pressure distribution was symmetrical about the centerline parallel to the feed shoe movement direction; and (4) neither the center die nor the right die always had higher pressure values than the other one at all locations. Comparison between cylindrical and toroidal dies indicated that: (1) neither of the two die shapes (cylinder and toroid) led to consistently higher or lower final pressure values at all locations and (2) for all three feed shoe speeds, the toroidal die had higher average final pressure values in the 0° orientation. 相似文献
40.
Z Chen A Spies R Hein X Zhou BC Thomas ML Richter P Gegenheimer 《Canadian Metallurgical Quarterly》1995,270(29):17124-17132
F1F0-ATP synthases utilize protein conformational changes induced by a transmembrane proton gradient to synthesize ATP. The allosteric cooperativity of these multisubunit enzymes presumably requires numerous protein-protein interactions within the enzyme complex. To correlate known in vitro changes in subunit structure with in vivo allosteric interactions, we introduced the beta subunit of spinach chloroplast coupling factor 1 ATP into a bacterial F1 ATP synthase. A cloned atpB gene, encoding the complete chloroplast beta subunit, complemented a chromosomal deletion of the cognate uncD gene in Escherichia coli and was incorporated into a functional hybrid F1 ATP synthase. The cysteine residue at position 63 in chloroplast beta is known to be located at the interface between alpha and beta subunits and to be conformationally coupled, in vitro, to the nucleotide binding site > 40 A away. Enlarging the side chain of chloroplast coupling factor 1 beta residue 63 from Cys to Trp blocked ATP synthesis in vivo without significantly impairing ATPase activity or ADP binding in vitro. The in vivo coupling of nucleotide binding at catalytic sites to transmembrane proton movement may thus involve an interaction, via conformational changes, between the amino-terminal domains of the alpha and beta subunits. 相似文献