scholarly journals A Modified Kwee van Woerden Algorithm with Reliable Error-Estimates

2020 ◽  
Author(s):  
Hans J. Deeg
Keyword(s):  
Error Estimates ◽  
Fundamental Problem ◽  
Space Mission ◽  
Original Method ◽  
External Input ◽  
Light Curves ◽  
Improved Method ◽  
Timing Error ◽  
Numerical Errors

The Kwee van Woerden (KvW) method for the determination of eclipse minimum times has been a staple in eclipsing binary research for decades, due its simplicity and independence of external input parameters. However, its estimates of the timing error have been known to be of low reliability. During the analysis of very precise photometry of CM Draconis eclipses from TESS space mission data, KvW’s original equation for the timing error estimate produced numerical errors, which evidenced a fundamental problem in this equation. This contribution introduces an improved way to calculate the timing error with the KvW method. A code that implements this improved method, together with several further updates over the original method is presented as well. An example application on the CM Draconis light curves from TESS is given, where we show that its timing error estimates of about 1 second are in excellent agreement with error estimates obtained by other means.

scholarly journals A Modified Kwee–Van Woerden Method for Eclipse Minimum Timing with Reliable Error Estimates

Galaxies ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 1
Author(s):  
Hans J. Deeg
Keyword(s):  
Error Estimates ◽  
Measurement Errors ◽  
Fundamental Problem ◽  
Space Mission ◽  
Original Method ◽  
External Input ◽  
Improved Method ◽  
Timing Error ◽  
Timing Errors

The Kwee–van Woerden (KvW) method used for the determination of eclipse minimum times has been a staple in eclipsing binary research for decades, due its simplicity and the independence of external input parameters, which also makes it well-suited to obtaining timings of exoplanet transits. However, its estimates of the timing error have been known to have a low reliability. During the analysis of very precise photometry of CM Draconis eclipses from TESS space mission data, KvW’s original equation for the timing error estimate produced numerical errors, which evidenced a fundamental problem in this equation. This contribution introduces an improved approach for calculating the timing error with the KvW method. A code that implements this improved method, together with several further updates of the original method, are presented. An example of the application to CM Draconis light curves from TESS is given. The eclipse minimum times are derived with the KvW method’s three original light curve folds, but also with five and seven folds. The use of five or more folds produces minimum timings with a substantially better precision. The improved method of error calculation delivers consistent timing errors which are in excellent agreement with error estimates obtained by other means. In the case of TESS data from CM Draconis, minimum times with an average precision of 1.1 s are obtained. Reliable timing errors are also a valuable indicator for evaluating if a given scatter in an O-C diagram is caused by measurement errors or by a physical period variation.

Improved Method for Determination of Triglycerides in Serum

1973 ◽  
Vol 19 (10) ◽  
pp. 1201-1202 ◽  
Author(s):  
Bruce P Neri ◽  
Christopher S Frings
Keyword(s):  
Confidence Level ◽  
Coefficient Of Variation ◽  
Room Temperature ◽  
Original Method ◽  
New Method ◽  
Improved Method ◽  
Serum Triglycerides ◽  
Accuracy And Precision ◽  
Significant Difference

Abstract We describe a new method for determination of serum triglycerides that is based on the original method of Fletcher [Clin. Chim. Acta22, 393 (1968)]. We have modified Fletcher’s reagents so that it is possible to saponify serum triglycerides in 5 min at room temperature (about 24 °C) instead of 60-70 °C for 15 min and to produce the final color in 15 min at 60-70 °C instead of 30 min at 50 ° C. The new reagents are stable for at least two months. The correlation coefficient obtained for the two methods (n = 107 sera) was 0.98. When the t test and F test were applied to these data, no significant difference in accuracy and precision was found at the 95% confidence level. The coefficient of variation (day-to-day) for the new method is 7.0%.

Distance to SN 1987A and the LMC

1999 ◽  
Vol 190 ◽  
pp. 549-554
Author(s):  
Nino Panagia
Keyword(s):  
Angular Size ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Light Curves ◽  
Distance Modulus ◽  
Absolute Size ◽  
Sn 1987A

Using the new reductions of the IUE light curves by Sonneborn et al. (1997) and an extensive set of HST images of SN 1987A we have repeated and improved Panagia et al. (1991) analysis to obtain a better determination of the distance to the supernova. In this way we have derived an absolute size of the ringRabs= (6.23 ± 0.08) x 1017cm and an angular sizeR″ = 808 ± 17 mas, which give a distance to the supernovad(SN1987A) = 51.4 ± 1.2 kpc and a distance modulusm–M(SN1987A) = 18.55 ± 0.05. Allowing for a displacement of SN 1987A position relative to the LMC center, the distance to the barycenter of the Large Magellanic Cloud is also estimated to bed(LMC) = 52.0±1.3 kpc, which corresponds to a distance modulus ofm–M(LMC) = 18.58±0.05.

SERUM TRIIODOTHYRONINE DETERMINATION BY SATURATION ANALYSIS

1973 ◽  
Vol 72 (4) ◽  
pp. 714-726 ◽  
Author(s):  
A. Burger ◽  
B. Miller ◽  
C. Sakoloff ◽  
M. B. Vallotton
Keyword(s):  
Ionic Strength ◽  
Limit Of Detection ◽  
Improved Method ◽  
Accuracy Of Measurement ◽  
Tracer Amount ◽  
The Mean ◽  
Physiological Values ◽  
Hyperthyroid Patients ◽  
Solvent Blank

ABSTRACT An improved method for the determination of serum triiodothyronine (T3) has been developed. After addition of a tracer amount of the hormone, T3 was extracted from 1 ml serum under conditions of pH and ionic strength which favoured T3 extraction (89%) over thyroxine (T4) extraction (58%). Chromatography of the extracted material on Sephadex LH-20 separated T3 completely from residual T4. The T3 eluate was dried, then re-dissolved in 0.5 ml NaOH 0.04 n. To 0.2 ml duplicate aliquots, a standard amount of TBG was added for the competitive protein analysis. After one hour incubation at 4°C, separation of bound from free T3 was achieved on small Sephadex G-25 columns. Overall recovery was 67 ± 10.8% and correction for the loss was made. The solvent blank was 37 ± 27 (sd) ng/100 ml. Accuracy of measurement of known quantities of T3 added to serum was 98.4%. The coefficient of variation within the assay was 6.2% and between the assays it was 11.4%. The limit of detection (0.1 ng) corresponded to a concentration of 25 ng/100 ml. T4 added to serum did not interfere with T3 determination until high non-physiological values were reached. The mean ± sd serum T3 in 54 euthyroid subjects was 153 ± 58 ng/100 ml and in 24 hyperthyroid patients it was 428 ±186 ng/100 ml; 4 out of the 24 hyperthyroid values were within 2 sd of the mean euthyroid group. All the values found in the euthyroid group were well above the limit of detection of the method.

An Improved Method for the Determination of Metabolic Fecal P

1957 ◽  
Vol 16 (1) ◽  
pp. 201-206 ◽  
Author(s):  
J. R. Luick ◽  
G. P. Lofgreen
Keyword(s):  
Improved Method

scholarly journals Geological Modeling Method Based on the Normal Dynamic Estimation of Sparse Point Clouds

Mathematics ◽  
2021 ◽  
Vol 9 (15) ◽  
pp. 1819
Author(s):  
Tiandong Shi ◽  
Deyun Zhong ◽  
Liguan Wang
Keyword(s):  
Point Cloud ◽  
Minimum Spanning Tree ◽  
Point Clouds ◽  
Original Method ◽  
Modeling Method ◽  
Geological Modeling ◽  
Improved Method ◽  
Normal Estimation ◽  
Sampling Points ◽  
Correct Point

The effect of geological modeling largely depends on the normal estimation results of geological sampling points. However, due to the sparse and uneven characteristics of geological sampling points, the results of normal estimation have great uncertainty. This paper proposes a geological modeling method based on the dynamic normal estimation of sparse point clouds. The improved method consists of three stages: (1) using an improved local plane fitting method to estimate the normals of the point clouds; (2) using an improved minimum spanning tree method to redirect the normals of the point clouds; (3) using an implicit function to construct a geological model. The innovation of this method is an iterative estimation of the point cloud normal. The geological engineer adjusts the normal direction of some point clouds according to the geological law, and then the method uses these correct point cloud normals as a reference to estimate the normals of all point clouds. By continuously repeating the iterative process, the normal estimation result will be more accurate. Experimental results show that compared with the original method, the improved method is more suitable for the normal estimation of sparse point clouds by adjusting normals, according to prior knowledge, dynamically.

Improved Method for the Determination of Ethylenebisdithiocarbamate Residues in Plants, Fruits, and Vegetables

1967 ◽  
Vol 50 (5) ◽  
pp. 1102-1108
Author(s):  
Charles F Gordon ◽  
Richard J Schuckert ◽  
William E Bornak
Keyword(s):  
Sulfuric Acid ◽  
Fruits And Vegetables ◽  
Analytical Procedure ◽  
Improved Method ◽  
Modified Method ◽  
Fungicide Residues ◽  
Crop Types ◽  
Large Representative

Abstract A modified method for the determination of dithiocarbamate fungicide residues on crops is presented. A large representative subsample of the frozen crop is blended in ice-cold deaerated water and an aliquot of the homogenate is added to the analytical apparatus containing hot 5 0% sulfuric acid. Dithiocarbamates are decomposed to evolve CS2 which is removed by a continuous gentle air-sweep from the digestion flask. Variations in technique allow the analysis of dithiocarbamate fungicide residues in several ranges, 1-10, 10-200, and 200-1000 /ig maneb. Recoveries from a wide variety of crops averaged 70 to 103%. Certain crop types present low recoveries and/or high apparent control values, but modifications in the analytical procedure are successful in solving these problems.

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