{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,22]],"date-time":"2025-11-22T17:02:14Z","timestamp":1763830934275,"version":"build-2065373602"},"reference-count":30,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2018,6,29]],"date-time":"2018-06-29T00:00:00Z","timestamp":1530230400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Gasoline engine oil (SAE 5W-20) was subjected to thermal oxidization (TO) for four periods of time (0 h, 48 h, 96 h and 144 h) and exposed to THz-time domain spectroscopy (TDS) measurement. Error contributions from various error sources, such as repeatability errors, assembly errors of the probe volume and errors caused by the TDS system were evaluated with respect to discernibility and significance of measurement results. The most significant error source was due to modifications of the TDS setup, causing errors in the range of 0.13% of the refractive index for samples with a refractive index around 1.467 and a probe volume length between 5 and 15 mm at 1 THz. The absorption coefficient error was in the range of 8.49% for an absorption around 0.6 cm\u22121. While the average of measurements taken with different setup configurations did not yield significant differences for different TO times, a single, fixed setup would be able to discern all investigated oil species across the entire frequency range of 0.5\u20132.5 THz. The absorption coefficient measurement showed greater discernibility than the measurement of the refractive index.<\/jats:p>","DOI":"10.3390\/s18072087","type":"journal-article","created":{"date-parts":[[2018,6,29]],"date-time":"2018-06-29T10:51:50Z","timestamp":1530269510000},"page":"2087","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":11,"title":["Error Sources and Distinctness of Materials Parameters Obtained by THz-Time Domain Spectroscopy Using an Example of Oxidized Engine Oil"],"prefix":"10.3390","volume":"18","author":[{"given":"Mario","family":"M\u00e9ndez Aller","sequence":"first","affiliation":[{"name":"Terahertz Systems Technology Group, Department of Electrical Engineering and Information Technology, Technische Universitat Darmstadt, Merckstr. 25, 64283 Darmstadt, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6730-0505","authenticated-orcid":false,"given":"Ali Mazin","family":"Abdul-Munaim","sequence":"additional","affiliation":[{"name":"Plant, Soil and Agricultural Systems, Southern Illinois University, MC 4415, Carbondale, IL 62901, USA"},{"name":"Department of Agricultural Machines and Equipment, College of Agriculture, Baghdad University, Baghdad 10071, Iraq"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0597-1581","authenticated-orcid":false,"given":"Dennis G.","family":"Watson","sequence":"additional","affiliation":[{"name":"Plant, Soil and Agricultural Systems, Southern Illinois University, MC 4415, Carbondale, IL 62901, USA"}]},{"given":"Sascha","family":"Preu","sequence":"additional","affiliation":[{"name":"Terahertz Systems Technology Group, Department of Electrical Engineering and Information Technology, Technische Universitat Darmstadt, Merckstr. 25, 64283 Darmstadt, Germany"}]}],"member":"1968","published-online":{"date-parts":[[2018,6,29]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"415","DOI":"10.1364\/OPEX.14.000415","article-title":"Detection and identification of explosive RDX by THz diffuse reflection spectroscopy","volume":"14","author":"Liu","year":"2006","journal-title":"Opt. Express"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"123","DOI":"10.1016\/j.triboint.2017.10.026","article-title":"Discriminating gasoline fuel contamination in engine oil by terahertz time-domain spectroscopy","volume":"119","author":"Preu","year":"2018","journal-title":"Tribol. Int."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"3032","DOI":"10.1063\/1.121531","article-title":"Characterization of optically dense, doped semiconductors by reflection THz time domain spectroscopy","volume":"72","author":"Jeon","year":"1998","journal-title":"Appl. Phys. Lett."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"363","DOI":"10.1007\/s10762-007-9217-9","article-title":"Properties of Building and Plastic Materials in the THz Range","volume":"28","author":"Piesiewicz","year":"2007","journal-title":"Int. J. Infrared Millim. Terahertz Waves"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"468","DOI":"10.1002\/mop.30322","article-title":"High accuracy terahertz time-domain system for reliable characterization of photoconducting antennas","volume":"59","author":"Abdulmunem","year":"2016","journal-title":"Microw. Opt. Technol. Lett."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1059","DOI":"10.1364\/JOSAB.25.001059","article-title":"Uncertainty in terahertz time-domain spectroscopy measurement","volume":"25","author":"Withayachumnankul","year":"2008","journal-title":"J. Opt. Soc. Am. B"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"610","DOI":"10.1007\/s10762-013-0042-z","article-title":"Fundamentals of Measurement in Terahertz Time-Domain Spectroscopy","volume":"35","author":"Withayachumnankul","year":"2014","journal-title":"J. Infrared Millim. Terahertz Waves"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"229","DOI":"10.1007\/s10762-016-0318-1","article-title":"Uncertainty in Terahertz Time-Domain Spectroscopy Measurement of Liquids","volume":"38","author":"Yang","year":"2017","journal-title":"J. Infrared Millim. Terahertz Waves"},{"key":"ref_9","unstructured":"Ornik, J., Watson, D.G., Balzer, J.C., and Koch, M. (September, January 27). Experimental characterization of dielectric parameter extraction uncertainty for low absorbing liquids using THz TDS. Proceedings of the 42nd International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz), Cancun, Mexico."},{"key":"ref_10","unstructured":"Lansdown, A.R. (2004). Lubrication and Lubricant Selection a Practical Guide, The American Society of Mechanical Engineers. [3rd ed.]."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"48","DOI":"10.1016\/j.triboint.2013.02.030","article-title":"Engine oil acidity detection using solid state ion selective electrodes","volume":"65","author":"Soleimani","year":"2013","journal-title":"Tribol. Int."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Mortier, R.M., Fox, M.F., and Orszulik, S.T. (2010). Chemistry and Technology of Lubricants, Springer. [3rd ed.].","DOI":"10.1023\/b105569"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"872","DOI":"10.1080\/10402004.2012.721921","article-title":"Proposal of an FTIR Methodology to Monitor Oxidation Level in Used Engine Oils: Effects of Thermal Degradation and Fuel Dilution","volume":"55","author":"Macian","year":"2012","journal-title":"Tribol. Trans."},{"key":"ref_14","first-page":"337","article-title":"Oxidation stability of gasoline engine lubricants: Effect of base-oil chemistry in laboratory and engine tests","volume":"5","author":"Faure","year":"1999","journal-title":"Lubr. Sci."},{"key":"ref_15","unstructured":"Zuidema, H.H. (1959). The Performance of Lubricating Oils, Reinhold Publishing Corporation."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"034105","DOI":"10.1063\/1.1999847","article-title":"Investigation of inflammable liquids by terahertz spectroscopy","volume":"87","author":"Ikeda","year":"2005","journal-title":"Appl. Phys. Lett."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"481","DOI":"10.1007\/s10762-006-9102-y","article-title":"THz wave sensing for petroleum industrial products","volume":"27","author":"Chen","year":"2006","journal-title":"Int. J. Infrared Millim. Terahertz Waves"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1658","DOI":"10.1109\/JPROC.2007.898835","article-title":"Terahertz Time-Domain Spectroscopy for Material Characterization","volume":"95","author":"Naftaly","year":"2007","journal-title":"Proc. IEEE"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1938","DOI":"10.1007\/s11433-009-0310-z","article-title":"Optical property and spectroscopy studies on the selected lubricating oil in the terahertz range","volume":"52","author":"Tian","year":"2009","journal-title":"Sci. China Ser. G"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"043901-1","DOI":"10.1088\/0256-307X\/29\/4\/043901","article-title":"Quantitative Analysis for Monitoring Formulation of Lubricating Oil Using Terahertz Time-Domain Transmission Spectroscopy","volume":"29","author":"Tian","year":"2012","journal-title":"Chin. Phys. Lett."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"687","DOI":"10.1007\/s10762-015-0164-6","article-title":"Distinguishing Gasoline Engine Oils of Different Viscosities using Terahertz Time-Domain Spectroscopy","volume":"36","author":"Reuter","year":"2015","journal-title":"Int. J. Infrared Millim. Terahertz Waves"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"795","DOI":"10.13031\/trans.59.11448","article-title":"Using terahertz time-domain spectroscopy to discriminate among water contamination levels in diesel engine oil","volume":"59","author":"Reuter","year":"2016","journal-title":"Trans ASABE"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"401","DOI":"10.1016\/0301-679X(89)90073-X","article-title":"Studies on the Ageing Characteristics of Automotive Crankcase oils","volume":"22","author":"Ofunne","year":"1989","journal-title":"Tribol. Int."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"3473","DOI":"10.1021\/ie000648k","article-title":"Assessment of oxidation in automotive crankcase lube oil: Effects of metal and water activity","volume":"41","author":"Egharevba","year":"2002","journal-title":"Ind. Eng. Chem. Res."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Peiponen, K.-E., Zeitler, A., and Kuwata-Gonokami, M. (2013). Terahertz Spectroscopy of Liquids and Biomolecules. Terahertz Spectroscopy and Imaging, Springer.","DOI":"10.1007\/978-3-642-29564-5"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1566","DOI":"10.1364\/AO.35.001566","article-title":"Refractive index of air: New equations for the visible and near infrared","volume":"35","author":"Ciddor","year":"1996","journal-title":"Appl. Optics"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"187","DOI":"10.2307\/1942661","article-title":"Pseudoreplication and the design of ecological field experiments","volume":"54","author":"Hurlbert","year":"1984","journal-title":"Ecol. Monogr."},{"key":"ref_28","unstructured":"SAS (2016). SAS Enterprise Guide 7.1, SAS Institute."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"699","DOI":"10.1007\/s10762-010-9669-1","article-title":"Uncertainty and Ambiguity in Terahertz Parameter Extraction and Data Analysis","volume":"32","author":"Funkner","year":"2011","journal-title":"J. Infrared Millim. Terahertz Waves"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"4335","DOI":"10.1364\/OE.15.004335","article-title":"Highly accurate optical material parameter determination with THz time-domain spectroscopy","volume":"15","author":"Pupeza","year":"2007","journal-title":"Opt. 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