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1

Study on uncertainty of inversion and resolution limit in the presence of noise

Luo C., Wang S., Yuan S.

Acta Geophysica

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2018

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Vol. 66, no. 5

1011--1018

EN

This study analyzed the uncertainty of inversion and the resolution limit in the presence of noise by means of statistical experiments. The exhaustive method is adopted to obtain the global optimal solution in each experiment. We found that even with small level of noise, solutions fluctuate in a large range for the thin bed. The distribution of solutions in the presence of noise is closely related to the spread of the cost function in the absence of noise. As a result, the area of a certain neighborhood around the true solution on the spread of the cost function in the absence of noise is used to evaluate the uncertainty of inversion and the resolution limit in the presence of noise. In the case that the SNR (signal-to-noise ratio) is 5 in this study, solutions focus around the true solution with a very small uncertainty only when the bed thickness is greater than the reciprocal of the double predominant frequency of the convoluting wavelet.

2

Comparison of float-sink and progressive release flotation of ground products of coal middlings

Xie W., He Y., Luo C., Zhang X., Li H., Yu J., Wang H., Shi F.

Physicochemical Problems of Mineral Processing

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2015

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Vol. 51, iss. 2

675--684

EN

An additional recovery of coking coal middlings can be utilized for increasing of the concentrate yield of coking coal. A combined flow sheet of comminution and flotation can realize this target. To investigate the effect of grinding process on further flotation of ground products, progressive release flotation tests were used to compare with the float-sink tests, which were regarded as a criterion. Coal middlings were ground by wet-milling with iron balls to <0.5 mm. Curves of ash vs. cumulative yields of sized products indicated that the concentrate yield of coal separated by progressive release flotation was lower than that of coal benefited by the float-sink test, with the same ash for four size fractions (0.5-0.25 mm, 0.25-0.125 mm, 0.125-0.074 mm and <0.074 mm). Distributions of elements conducted by energy disperse spectroscopy (EDX) showed that associated kaolinite was liberated and exposed on the surface. It led to the shift of local surface property from hydrophobicity to hydrophilicity. Meanwhile, analyses of chemical property performed by an X-Ray photoelectron spectrometer (XPS) depicted that the hydrophilic mineral FeOOH, which generated in the grinding process, was adsorbed on the coal surface. Flotation of the ground products were worsened due to the increase of hydrophilicity of the coal surface.

3

The gas response of hydroxyl modified SWCNTs and carboxyl modified SWCNTs to H2S and SO2

Zhang X., Yang B., Dai Z., Luo C.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 7b

311--314

EN

H2S and SO2 are important characteristic gases reflecting latent insulated defects in gas insulated switchgear (GIS).The detection of the H2S and SO2 is of great significance to diagnose and assess the operating status of GIS. In this paper, the single-walled carbon nanotubes (SWCNTs) are modified by hydroxyl and carboxyl, respectively. The gas sensing response of the modified SWCNTs to H2S and SO2 are studied. The results show that the sensitivity of SWCNTs modified by carboxyl is higher than that of SWCNTs modified by hydroxyl to H2S, the same for SO2.

PL

Przedstawiono metodę detekcji H2S iSO2 jako możliwość oceny stanu izolacji przełączników gazowych GIS. Jako czujnik wykorzystano nanorurki węglowe SWCNTs modyfikowane przez wodorotlenki hydroxyl i carboxyl.

4

Experimental study of a small gas-puff Z-pinch device

Luo C., Wang X., Zou X.

Nukleonika

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2006

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Vol. 51, nr 1

43-46

EN

A small gas puff Z-pinch device has been constructed and operated. The device has the parameters: the capacitance of energy storage capacitors 16 mi F, charging voltage 22 kV, peak current 210 kA and a quarter of current period 2.4 mi s. A three-frame Mach-Zehnder interferometer and a compact Thomson ion energy analyzer were developed for Z-pinch plasma experiment. According to the results of diagnostics, the electron density ne of the plasma right before pinch instant is larger than 5.4 × 1019/cm3, the corresponding pinch velocity v of the plasma sheath is 9.0 cm/ěs. Clear parabolas produced by neon ions Ne+, Ne2+, Ne3+ and Ne4+ on CR-39 target have been observed. The energy spectra dN/dTdů for Ne+, Ne2+, Ne3+ and Ne4+ ions were determined. The highest energies of Ne+, Ne2+, Ne3+ and Ne4+ ions emitted from our Z-pinch plasma are below 1.3 MeV.