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Leng W.-X.,China University of Petroleum - Beijing | Leng W.-X.,Key Laboratory of Oil and Gas Terahertz Spectroscopy and Photoelectric Detection | Ge L.-N.,China University of Petroleum - Beijing | Xu S.-S.,Polytechnic University of Mozambique | And 3 more authors.
Chinese Physics B | Year: 2014

Heptafluoropropane (HFP), as the best alternative to halon fire-suppression agents, is now a widely used fire extinguishing agent. The current studies of HFP, concentrating on the extinguishing mechanisms of flames and decomposition products, in general deal with the destructive and high temperature cases. In this paper, terahertz time-domain spectra are used to characterize HFP at different pressures. Optical parameters of HFP, such as absorption coefficient, refractive index, and relative permittivity, and their relationship with concentration of samples, are discussed. The absorption peak of HFP at 0.3 THz depends strongly on the applied pressure, and the corresponding parameters increase almost linearly with increasing HFP concentration. The present study lays a foundation for future extensive applications. © 2014 Chinese Physical Society and IOP Publishing Ltd. Source


Li Q.,China University of Petroleum - Beijing | Li Q.,Key Laboratory of Oil and Gas Terahertz Spectroscopy and Photoelectric Detection | Zhao K.,China University of Petroleum - Beijing | Zhao K.,Key Laboratory of Oil and Gas Terahertz Spectroscopy and Photoelectric Detection | And 5 more authors.
Science China: Physics, Mechanics and Astronomy | Year: 2014

The goal of continuous ambient participate monitoring has been accomplished by the use of terahertz (THz) wave. The frequency-dependent spectrum and absorbance of the particulate matter (PM2.5) were measured in the range of 0–10 THz. The PM2.5 concentration ρ was calculated according to the sampling time and air flow. With the increase of ρ, the THz wave amplitude gradually decreased and the absorbance A of PM2.5 increased. The relationship between r and A can be described mathematically through ρ ∝ A0.5. Our results demonstrate that the terahertz wave could be a valuable tool to monitor and inspect the PM2.5 concentration. © 2014, Science China Press and Springer-Verlag Berlin Heidelberg. Source


Jin W.-J.,State Key Laboratory of Petroleum Resources and Prospecting | Jin W.-J.,China University of Petroleum - Beijing | Jin W.-J.,Key Laboratory of Oil and Gas Terahertz Spectroscopy and Photoelectric Detection | Zhao K.,State Key Laboratory of Petroleum Resources and Prospecting | And 6 more authors.
Applied Geophysics | Year: 2013

We measured the water content (0.01%-0.25% w/w) in crude oil emulsions using terahertz time-domain spectroscopy (THz-TDS). To improve the precision and range of the measurements, we used 1 and 10 mm thick quartz cells. The experiments were performed at 20 °C and the THz wave was transmitted vertically to the samples and detected on the other side. The experimental results suggest linear relation for the THz absorption coefficient and the water content of the crude oil emulsions in the observed range. The linear dependence facilitates high-precision measurements of the water content of crude oil. This suggests the potential of THz-TDS in determining the water concentration in crude oil and borehole fluid identification. © 2013 Editorial Office of Applied Geophysics and Springer-Verlag Berlin Heidelberg. Source


Qin F.,China University of Petroleum - Beijing | Qin F.,Key Laboratory of Oil and Gas Terahertz Spectroscopy and Photoelectric Detection | Li Q.,Key Laboratory of Oil and Gas Terahertz Spectroscopy and Photoelectric Detection | Zhan H.,Key Laboratory of Oil and Gas Terahertz Spectroscopy and Photoelectric Detection | And 4 more authors.
Science China: Physics, Mechanics and Astronomy | Year: 2014

Terahertz time-domain spectroscopy (THz-TDS) was used for the quantitative detection of sulfur content in gasoline. Models of chemo metrics methods and partial least squares (PLS) were built to measure THz-TDS and the sulfur content. All of the samples were divided into two parts. One part was used for calibration and the other one for validation. In order to evaluate the quality of the models, the correlation coefficient (R) and root-mean-square errors (RMSE) of calibration and validation models were calculated. The value of R and RMSE were close to 1 and 0 within acceptable levels, respectively, indicating that the combination of THz-TDS and PLS is a potential method for further quantitative detection. © 2014 Science China Press and Springer-Verlag Berlin Heidelberg. Source


Jiang C.,China University of Petroleum - Beijing | Jiang C.,Key Laboratory of Oil and Gas Terahertz Spectroscopy and Photoelectric Detection | Zhao K.,China University of Petroleum - Beijing | Zhao K.,Key Laboratory of Oil and Gas Terahertz Spectroscopy and Photoelectric Detection | And 5 more authors.
Energy and Fuels | Year: 2014

Magnetic technology can significantly change the characteristics of crude oil, and the physical mechanism has received much attention for several years. To date, there is not yet an accurate conclusion. Terahertz time-domain spectroscopy is employed in this paper to characterize the optical parameters of selected wax-bearing crude oil under the action of a magnetic field. The corresponding absorption coefficient and extinction coefficient of samples are obtained by a fast Fourier transform frequency domain spectrum, and the aggregation characteristics of particles are analyzed in crude oil under a magnetic field. The decrease of the extinction coefficient may be suggested as qualitative proof of a magnetic-field-induced disaggregation of the suspended colloidal particles. Terahertz time-domain spectroscopy may be a powerful tool to characterize the particle disaggregation state in crude oil. © 2014 American Chemical Society. Source

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