Abstract-Discriminating gasoline fuel contamination in engine oil by terahertz time-domain spectroscopy

Ali MazinAbdul-Munaim, MarioMéndez Aller, SaschaPreu, Dennis G. Watson

http://www.sciencedirect.com/science/article/pii/S0301679X17304917

Gasoline engine oil (SAE 5W20) was contaminated with four levels (0%, 4%, 8% and 12%) of gasoline fuel and submitted to terahertz time-domain spectroscopy (THz-TDS). Three sampling methods were used to compare measurement variations. For all sampling methods, refractive index decreased with increased fuel contamination and absorption coefficient increased with increased fuel contamination. Absorption coefficients were significantly different for each fuel contamination level for each sampling method across the entire 0.5–2.5 THz range. The frequency of 0.5 THz produced the best model of absorption coefficient predicting fuel contamination with a root-mean-square error of 0.21% points. THz-TDS demonstrated high potential for estimating gasoline fuel contamination in gasoline engine oil.

Terahertz spectroscopy plus analysis distinguishes gasoline mixtures

By John Wallace
Senior Editor

http://www.laserfocusworld.com/articles/print/volume-49/issue-11/newsbreaks/terahertz-spectroscopy-plus-analysis-distinguishes-gasoline-mixtures.html

It is important in the petroleum industry to be able to characterize different refined-oil mixtures, which include diesel/gasoline and gasoline/gasoline (different octane grades); one way to do this is with  terahertz time-domain spectroscopy, which takes advantage of the fact that different kinds of oil have different terahertz-frequency characteristics. However, in some instances, this approach has not been precise enough: for example, when testing mixtures of 90# and 97# gasoline, the absolute error between the real and fitted value was too large (25%). Now, researchers at Tianjin University (Tianjin, China) and North Automatic Control Technology Institute (Taiyuan, China) have improved this approach by subjecting it to a multiparameter combined analysis, which reduced the absolute error in the example case to 6%.

Terahertz time-domain waveforms of the samples were acquired using a mode-locked Ti:sapphire ultrafast laser to generate electron-hole pairs that created single-cycle terahertz pulses, which were then focused by parabolic optics to a 3.5 mm spot. Changing the relative time delay between a gated pulse and the detected pulse allowed the pulse shape to be mapped out. Absorption-
coefficient spectra of the sample (which was placed in a quartz cell) were taken. The analysis was based on four parameters, two time-related and the other two absorption-related. Eleven gasoline-mixture samples were tested. The researchers believe most types of oil mixtures can be tested this way. Contact Jian Li at tjupipe@tju.edu.cn.

Terahertz time-domain spectroscopy quantifies refined-oil mixtures

http://www.laserfocusworld.com/articles/print/volume-48/issue-09/newsbreaks/terahertz-time-domain-spectroscopy-quantifies-refined-oil-mixtures.html

To save infrastructure costs, different types of refined oil are often transported over a single pipe at alternate times. Consequently, sensors that can easily, quickly, and safely determine the proportions of components in a refined-oil mixture are invaluable for tracking, routing, and ultimately rerefining the mixtures. Scientists at Tianjin University (Tianjin, China) are now experimenting withterahertz time-domain spectroscopy at frequencies between 0.25 and 1.5 THz to determine the proportions in a mixture of gasoline and diesel.

In the time-domain spectroscopy (TDS) system, 50 fs pulses at an 800 nm wavelength from a Ti:sapphire laser are split into pump and detection pulses, with the pump pulse used to stimulate terahertz radiation from a photoconductive antenna and the detection pulse acting on a photoconductive-antenna detector in concert with the terahertz signal. Information from reference and sample pulses are Fourier-transformed to provide the refractive index and absorption coefficient of the oil mixtures.

Mixtures of 97# gasoline and -10 diesel with a sample thickness of 10 mm were measured. Results for the gasoline component were very accurate, but the results were a mean of 4.3% off for the diesel—the latter to be corrected by adopting a modified form of the Beer-Lambert absorption-coefficient law. Contact Yi-nan Li at lin860405@gmail.com.

Terahertz and measurement of oil, gasoline and fluid particle accumulation/ streams

Corning patent
Corning patent recognizing use of API/Picometrix T-Ray 4000
METHODS OF CHARACTERIZING AND MEASURING PARTICULATE FILTER ACCUMULATION

Abstract
Methods of characterizing and measuring particulate accumulation in a family of particulate filters (10) are disclosed. The disclosure can be applied to diesel, gasoline and natural gas fueled engines, fluid streams bearing dust, and chemical and biological substances such as may be found in laboratory fluids, for example, air. In one embodiment, the disclosure is directed to measuring diesel particulate accumulation in a family of diesel particulate filters. The methods include measuring calibration complex terahertz transmission spectra (P.sub.C(f)) of at least a portion (17) of at least one particulate or diesel particulate filter in the family for different known particulate or diesel particulate amounts (A.sub.DP). The method also involves performing a partial least squares (PLS) analysis on the calibration complex terahertz transmission spectra to establish a calibration relationship between the complex terahertz transmission spectra and the particulate or diesel particulate amounts. The complex transmission spectrum of a subject particulate filter or diesel particulate filter having an unknown amount of particulate or diesel particulate accumulation is then determined and compared to the linear calibration relationship to establish a measured amount of particulates or diesel particulates. The methods include using a terahertz (THz) system (100) to obtain the complex terahertz transmission spectra for the calibration and subject particulate or diesel particulate filters.
Inventors:
Gunasekaran; Natarajan; (Painted Post, NY) ; Schneider; Vitor Marino; (Painted Post, NY) ; Smith; Charlene Marie; (Corning, NY) ; Williams; Carlo Anthony Kosik; (Painted Post, NY)
Correspondence Name and Address:
CORNING INCORPORATED SP-TI-3-1 CORNING NY 14831 US

Example THz-TDS systems are described in U.S. Pat. No. 5,710,430 and Pre-Grant Published U.S. Patent Application No. 2008/0137068, which patent and which patent application are incorporated by reference herein. A suitable THz-TDS system adaptable for use in carrying out the methods of the present invention is the T-Ray 4000.TM. system available from Picometrix Inc., of Ann Arbor, Mich.

http://www.freepatentsonline.com/20100108890.pdf