Accuracy Assessment Of Method Research Articles

EVALUATION OF ACCURACY OF DIGITAL TERRAIN MODELING METHODS BASED ON SPATIAL INTERPOLATION (Part 2)

Digital terrain model (DTM) is an integral part of many geodetic works. It allows accurately reproducing the earth's surface in a digital form with varying levels of detail. One of the most significant problems in creating a DTM is the accuracy of reflecting the relief. In the first part of the work, an analysis of methods that can more detailed reflect the relief was already conducted. For these purposes, the Surfer geoinformation package was selected, which offers a considerable number of methods based on the spatial interpolation algorithm. Although these methods have represented the same area with high detail, there is still a need to assess the accuracy of each method. The purpose of this article is to assess the accuracy of methods for constructing a digital terrain model based on spatial interpolation. Since model accuracy is a crucial factor for many geodetic works, it is necessary to determine which methods are the most accurate and meet the requirements of different purposes of use. The accuracy assessment of methods will improve the efficiency of geodetic works and avoid errors and additional costs. In the Surfer program, after constructing the DTM with each method, a report can be obtained containing the input values of points and the values obtained after interpolation with each method. This report is very useful for assessing the accuracy of each method since it allows understanding how well the model reflects the real relief. To assess the accuracy of each method, control points of the spatial variable Z were taken, and the values in these points were interpolated for each method. This assessment makes it possible to obtain a numerical characteristic of accuracy for each method and compare them with each other. Based on the analysis conducted, it can be concluded that problematic areas were identified on a fragment of a topographic map, where there were insufficient input data for accurate interpolation. The result is not accurate and could be better with input data obtained from geodetic instruments and technologies such as GPS, lidar, etc. The "Natural Neighbor" method performed the best in reproducing the digital elevation model on this hilly terrain. The application of the "Kriging," "Triangulation with Linear Interpolation," "Modified Shepard's Method," and "Radial Basic Function" methods provided fairly accurate interpolation. However, the "Minimum Curvature" method was found to be ineffective in hilly terrain as it did not provide accurate interpolation. After conducting an accuracy assessment, it can be concluded that high-quality input data is an extremely important element in achieving more accurate results when creating a digital elevation model. Keywords: digital elevation model, construction methods, spatial interpolation, geographic information system, Surfer.

Enhancing the specificity of chitin determinations through glucosamine analysis via ultra-performance LC-MS.

As chitin is gaining an increased attention as feedstock for industry, quantification thereof is becoming increasingly important. While gravimetric procedures are long, not specific and highly labour-intensive, acidic hydrolysis of chitin into glucosamine followed by quantification of the latter is more performant. Even though several quantification procedures for the determination of chitin can be found in the literature, they give inconsistent results and their accuracy was not assessed due to the lack of certified analytical standards. Therefore, in the present study, commercially available chitin from practical grade was characterised in detail, allowing the assessment of method accuracy. The procedure for the hydrolysis of chitin into glucosamine and subsequent quantification via UPLC-MS was investigated in detail as well. Using 9-fluorenylmethyl chloroformate (FMOC-Cl) as derivatisation reagent, glucosamine was quantified using reversed-phase chromatography. For the chitin hydrolysis, the highest glucosamine recovery was obtained with 8.0M HCl for 2h at 100°C. The entire procedure for chitin quantification, including the hydrolysis, was characterised by high interday and intraday precision and accuracy. The specificity of the procedure was assessed as well by analysing different mixtures of cellulose and chitin. Chitin recoveries from these analyses ranged from 98.8 to 105.8% while no signal was observed for 100% cellulose, indicating the high specificity of the procedure. It was also concluded that the procedure is much faster and less labour-intensive compared to the gravimetric procedure.

Quantitative 1H NMR analysis of a difficult drug substance and its exo-isomer as hydrochloride salts using alkaline deuterated methanol

Quantitative NMR is extremely useful for rapid determination of sample purity. Occasionally however, certain ionic compounds (prepared as a salt with a counter ion) may be difficult to accurately quantitate, due to aggregation, solubility, and/or signal drift. Here we describe an example of utilizing alkaline deuterated methanol for quantitative NMR of a problematic endo drug substance and its exo-isomer, as hydrochloride salts, with precision comparable to HPLC. This method allows for in situ neutralization of the HCl salt and subsequent solubilization of the organic free-base for analysis, providing a one-step quantitative sample preparation procedure. The selection of solvent, alkaline concentration, internal standard, instrumental parameters, and assessment of method accuracy are discussed. Overall, the method is simple, cost-effective, and analytically reliable.

Accuracy Assessment of Methods for Predicting Dry Dock Block Reactions

The current state of the art in dry docking engineering prediction and analysis of block reactions is the widely used so-called Crandall's method. Unfortunately, Crandall's method, although simple to use, is highly simplified and can be quite inaccurate in some cases. In this paper the author summarizes work that was undertaken at the University of New Orleans and Northrop Grumman Ship Systems Avondale Operations(Taravella 2003) in order to investigate the use of more accurate although more complicated methods and then to compare these results to full-scale actual measured values from the Northrop Grumman Ship Systems' dry dock. Recommendations are then made regarding the selection of suitable methods for predicting block reactions accurately.

Determination of Acesulfame and Sucralose in Oral Electrolyte Maintenance Solution by Liquid Chromatography

A method was developed for the direct, simultaneous determination of acesulfame and sucralose in oral electrolyte maintenance solution (OEMS). Analyte separation and quantitation were achieved by gradient reversed-phase liquid chromatography (LC) and UV absorbance at 192 nm, respectively. Detection at a second wavelength, 214 nm, was used to check sucralose peak purity; 20 microL OEMS was injected without preparation or dilution. System linearity was demonstrated as 192 nm peak area versus analyte concentration at 80-120% OEMS sweetener fortification (r > 0.999, and all residuals < 0.5%, for both acesulfame and sucralose). Spike recoveries for OEMS samples prepared at 3 spiking levels (80, 100, and 120% sweetener fortification) ranged from 100.3 to 102.0% for acesulfame, and from 97.9 to 102.3% for sucralose. In a second assessment of method accuracy, the same spiked OEMS samples were tested by 2 alternative methods: acesulfame (LC/UV at 230 nm) and sucralose (anion exchange-pulsed amperometric detection). Results for the alternative acesulfame method were within 1.2%, and for the alternative sucralose method within 6.0%, of the corresponding results obtained by the 192 nm method. Repeatability and intermediate precision RSD values were < 1 % for acesulfame and < 3% for sucralose. The limits of quantitation were 1.6 and 32 mg/L for acesulfame potassium and sucralose, respectively. Despite the weak UV absorptivity of sucralose and the consequent small size of its LC peak, no evidence was found for sucralose interference in any of the commercial OEMS flavors.