Search results for "near-infrared"
showing 10 items of 180 documents
An integrated approach for high spatial resolution mapping of water and carbon fluxes using multi-sensor satellite data
2012
In the last years, modeling of surface processes - such as water, energy and carbon budgets, as well as vegetation growth- seems to be focused on integrated approaches that combine aspects of hydrology, biology and meteorology into unified analyses. In this context, remotely sensed data often have a core role due to the cross-cutting impact of this novel source of spatially distributed information on all these research areas. However, several applications - such as drought monitoring, yield forecasting and crop management - require spatially detailed products at sub-field scales, which can be obtained only with support of adequately fine resolution remote sensing data (< 100 m). In particul…
The scattering and re-absorption of red and near-infrared chlorophyll fluorescence in the models Fluspect and SCOPE
2019
Scattering and re-absorption have been recognized as relevant aspects for the interpretation of solar induced chlorophyll fluorescence (SIF) in vegetation remote sensing. In an earlier study [Yang and Van der Tol, RSE 215, 97–108, 2018] we addressed the problem of scattering and re-absorption of near-infrared fluorescence in the vegetation canopy. In this study we analyse within-leaf re-absorption of both red and near-infrared fluorescence using the radiative transfer model Fluspect. The leaf scattering determines the ratio of backward to total leaf fluorescence emission Fb/(Fb + Ff). Fluspect reproduces this ratio with an RMSE of less than 0.1, and explains the observed dependence of the s…
Near-infrared imaging and structured light ranging for automatic catheter insertion
2006
Vein localization and catheter insertion constitute the first and perhaps most important phase of many medical procedures. Currently, catheterization is performed manually by trained personnel. This process can prove problematic, however, depending upon various physiological factors of the patient. We present in this paper initial work for localizing surface veins via near-infrared (NIR) imaging and structured light ranging. The eventual goal of the system is to serve as the guidance for a fully automatic (i.e., robotic) catheterization device. Our proposed system is based upon near-infrared (NIR) imaging, which has previously been shown effective in enhancing the visibility of surface vein…
Hydration Chemistry of Cement Studied by Near Infrared Spectroscopy
2018
Cement is a complex mixture of inorganic compounds which mainly composed of calcium silicates and calcium aluminates. Cement is mixed with water to form concrete. During the mixing calcium silicate hydrate (CSH) and calcium hydroxide are formed. The ratio of water/cement (w/c ratio) is important to obtain a mixture that gives optimum strength to the concrete. In this work, three different cement samples were mixed with water in four different ratios, including 0.35, 0.40, 0.45 and 0.55, respectively. The hydration process of cement was investigated by using near infrared (NIR) spectroscopy over a period of 28 days. The combination frequency of OH stretching and bending of water molecules gi…
Quantitative Determination of Calcium Hydroxide by using Near Infrared Spectroscopy
2018
Calcium hydroxide (CH) is a by-product from hydration reaction of cement along with calcium silicate hydrate (C-S-H) gel. It helps to protect the steel reinforcements in concrete structures from corrosion process due to carbonation. The presence of calcium hydroxide provides a basic environment (pH˃10) that induces the formation of passive oxide film and keeps steel structures from corrosion. The detection and quantification of calcium hydroxide in concrete structures are important to understand the nature and state of the steel structures in concretes. In this research work, the variation of calcium hydroxide to calcium silicate ratios in cement were measured by using near-infrared spectro…
Application of infrared spectroscopy as Process Analytics Technology (PAT) approach in biodiesel production process utilizing Multivariate Curve Reso…
2019
Abstract Process Analytical Technology means at-line collection of analytical information from the process when the reaction is in progress. Obtained information enables process engineers to better control the Critical Process Parameters and direct the reaction to desirable routs. Near-infrared spectroscopy due to its analytical features, as well as the high capability of automation, versatile sampling and spectral acquisition methods is a useful tool in process monitoring when coupled to chemometrics. The Multiple Scatter Correction preprocessing technique and Alternative Least Square method can extract spectral and concentration information of a reaction mixture simultaneously, were emplo…
Determination of Olive Oil Parameters by Near Infrared Spectrometry
2010
Publisher Summary Near infrared (NIR) covers the region between 780 and 2500 nm, and based on the absorption, transmission or reflection of the light, NIR spectroscopy provides a fast and non-destructive technique which is very useful for the simultaneous determination of several compounds in the same sample. Food NIR spectra comprise broad bands corresponding to overtones and combinations of vibrational modes involving C–H, O–H, and N–H chemical bonds, providing a great amount of information which properly treated by chemometrics is useful for classification and for the quantification of many parameters. The olive oil extraction process starts in the harvesting and transport of olive fruit…
Quantitative determination of surface area of silica gel particles by near infrared spectroscopy and chemometrics
2008
Abstract Surface areas of silica gel particles have been quantitatively determined by using near infrared spectrometry and chemometrics. Surface areas of six silica gel samples with varying surface area (300–750 m2/g) have been determined by the common Brunauer–Emmett–Teller (BET) method and used in preparing mixtures of silica gel samples with varying surface area in the ranges 300–474 and 500–750 m2/g. The near infrared spectra of the mixtures were measured and the spectral profiles calibrated against the calculated surface area of the mixtures as dependent variable using partial least squares (PLS) technique. The models obtained from the calibrations were then used in predicting the surf…
Field non-destructive determination of nectarine quality under deficit irrigation
2021
This study investigated the effects of deficit irrigation (DI) at different fruit growth stages and tree orientation on fruit quality of ‘September Bright’ nectarines (Prunus persica L. Batsch). Control trees were fully irrigated throughout the entire fruit development period, whereas deficit irrigation was supplied at fruit growth stage I (cell division, DI-I), II (pit hardening, DI-II), IIIa (cell expansion, DI-IIIa) and IIIb (fruit maturation, DI-IIIb). Non-destructive measurements of fruit maturity and quality were carried out using portable devices based on near-infrared spectrometry and pigment fluorescence on west- and east-oriented trees of an Open Tatura system. Chlorophyll degrada…
Fast authentication of tea tree oil through spectroscopy
2018
Two new procedures, based on infrared spectroscopy in the near infrared (NIR) and mid infrared (MIR), have been developed for the authentication of tea tree oil (TTO) commercial samples. Infrared measurements were made on untreated samples by transmission NIR and attenuated total reflectance (ATR) followed by partial least square discriminant analysis (PLS-DA). These methods offer a fast and low cost alternative to enantiomeric two-dimensional gas chromatography coupled to mass detection usually employed to discriminate between authentic and non-authentic samples. In these studies, a set of 267 samples, including authentic and non-authentic labelled tea tree oil samples, were used to build …