scholarly journals Spatially resolved measurements of the solar photospheric oxygen abundance

2020 ◽  
Vol 643 ◽  
pp. A142
Author(s):  
M. Cubas Armas ◽  
A. Asensio Ramos ◽  
H. Socas-Navarro
Keyword(s):  
Systematic Errors ◽  
Model Atmosphere ◽  
Nuisance Parameters ◽  
Hierarchical Bayesian Model ◽  
Random Errors ◽  
Vacuum Tower ◽  
Oxygen Abundance ◽  
Spatially Resolved ◽  
Good Agreement

Aims. We report the results of a novel determination of the solar oxygen abundance using spatially resolved observations and inversions. We seek to derive the photospheric solar oxygen abundance with a method that is robust against uncertainties in the model atmosphere. Methods. We use observations with spatial resolution obtained at the Vacuum Tower Telescope to derive the oxygen abundance at 40 different spatial positions in granules and intergranular lanes. We first obtain a model for each location by inverting the Fe I lines with the NICOLE inversion code. These models are then integrated into a hierarchical Bayesian model that is used to infer the most probable value for the oxygen abundance that is compatible with all the observations. The abundance is derived from the [O I] forbidden line at 6300 Å taking into consideration all possible nuisance parameters that can affect the abundance. Results. Our results show good agreement in the inferred oxygen abundance for all the pixels analyzed, demonstrating the robustness of the analysis against possible systematic errors in the model. We find a slightly higher oxygen abundance in granules than in intergranular lanes when treated separately (log(ϵO) = 8.83 ± 0.02 vs. log(ϵO) = 8.76 ± 0.02), which is a difference of approximately 2-σ. This tension suggests that some systematic errors in the model or the radiative transfer still exist but are small. When taking all pixels together, we obtain an oxygen abundance of log(ϵO) = 8.80 ± 0.03, which is compatible with both granules and lanes within 1-σ. The spread of results is due to both systematic and random errors.

Statistics and parallaxes

1978 ◽  
Vol 48 ◽  
pp. 7-29
Author(s):  
T. E. Lutz
Keyword(s):  
Experimental Design ◽  
Statistical Methods ◽  
Review Paper ◽  
Systematic Errors ◽  
Past Experience ◽  
Random Errors ◽  
Trigonometric Parallaxes ◽  
Systematic And Random Errors

This review paper deals with the use of statistical methods to evaluate systematic and random errors associated with trigonometric parallaxes. First, systematic errors which arise when using trigonometric parallaxes to calibrate luminosity systems are discussed. Next, determination of the external errors of parallax measurement are reviewed. Observatory corrections are discussed. Schilt’s point, that as the causes of these systematic differences between observatories are not known the computed corrections can not be applied appropriately, is emphasized. However, modern parallax work is sufficiently accurate that it is necessary to determine observatory corrections if full use is to be made of the potential precision of the data. To this end, it is suggested that a prior experimental design is required. Past experience has shown that accidental overlap of observing programs will not suffice to determine observatory corrections which are meaningful.

scholarly journals Numerical Uncertainty in Density Estimation for Background Oriented Schlieren

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Jiacheng Zhang ◽  
Lalit Rajendran ◽  
Sally Bane ◽  
Pavlos Vlachos
Keyword(s):  
Density Gradient ◽  
Systematic Uncertainty ◽  
Density Measurement ◽  
Random Errors ◽  
Target Pattern ◽  
Density Estimates ◽  
Total Uncertainty ◽  
Spatially Resolved ◽  
Background Oriented Schlieren ◽  
Good Agreement

Background Oriented Schlieren (BOS) is an image-based density measurement technique. BOS estimates the density gradient from the apparent distortion of a target pattern viewed through a medium with varying density using cross-correlation, tracking, or optical flow algorithms. The density gradient can then be numerically integrated to yield a spatially resolved estimate of the density [1]. A method was recently proposed to estimate the a-posteriori instantaneous and spatially resolved density uncertainty for BOS [2] and showed good agreement between the propagated uncertainties and the random error. However, the density uncertainty quantification method could not account for the systematic uncertainty in the density field due to the discretization errors introduced during the numerical integration, which could be much larger than the displacement random errors [2]. In this work, we propose a method to estimate the numerical uncertainty introduced by the density integration in BOS measurements, using a Richardson extrapolation framework. A procedure is also introduced to combine this systematic uncertainty with the random uncertainty from the previous work to provide an instantaneous, spatially-resolved total uncertainty on the density  estimates. The method will be tested with synthetic fields and synthetic BOS images.

scholarly journals The calculation of errors and the choice of sampling times in the determination of irreversible disposal rates in vivo by isotope experiments

1975 ◽  
Vol 152 (2) ◽  
pp. 417-420 ◽  
Author(s):  
Dennis F. Heath ◽  
Vincent J. Cunningham
Keyword(s):  
Specific Radioactivity ◽  
Systematic Errors ◽  
British Library ◽  
Small Animals ◽  
Random Errors ◽  
Basic Language ◽  
Sampling Times ◽  
Label Time

In well-known methods of estimating rates of irreversible disposal (utilization) in vivo the rates are calculated from the areas to infinity under specific radioactivity–time (S–t) or quantity-of-label–time (q–t) curves obtained by measurements on samples of plasma after intravenous injection of labelled substrate. The errors in the calculated rates are mostly those of the estimates of the areas. These errors are of two kinds: random, caused by the variances of the values of S or q, and systematic, caused by differences between the curves used to interpolate between these values and the true curves. A rigorous method is given for calculating the random errors from the variances of the values of S or q, and is applied to choosing the best times to sample the plasma from small animals from which few plasma samples can be taken. A procedure for estimating systematic errors is also given. Programs in BASIC language to carry out the calculations are deposited as Supplementary Publication SUP 50058 (5 pages) at the British Library (Lending Division), Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms given in Biochem. J. (1975) 145, 5.

scholarly journals Absolute Determinations of Star Declinations From Pole to Pole

1990 ◽  
Vol 141 ◽  
pp. 67-67
Author(s):  
V.A. Naumov
Keyword(s):  
Systematic Errors ◽  
Method Of Determination ◽  
Image Position ◽  
Good Agreement

The most widely spread method of determination of star declinations is Bessel's method. Alhough it gives good agreement between star declinations obtained from observations of stars in upper and lower culminations, it leads to great systematic errors if the system of the instrument has an error of the type such as flexure or errors of divided circle. Besides, in the determination of correction of latitude (Δφ) and refraction (Δμ) considerable correlation between them exists.

Determination of Drag of Jet-Propelled Aircraft in Flight

1949 ◽  
Vol 1 (1) ◽  
pp. 89-100 ◽  
Author(s):  
G. W. Trevelyan ◽  
D. R. Blundell
Keyword(s):  
Engine Performance ◽  
Systematic Errors ◽  
Minor Importance ◽  
Low Mach Number ◽  
Usual Procedure ◽  
Engine Thrust ◽  
Accurate Knowledge ◽  
Full Knowledge ◽  
Good Agreement

In order to obtain full knowledge of the performance of an aircraft, one of the important quantities to be determined is the drag. The usual procedure is to measure the level speed of the aeroplane and to calculate the drag under these conditions from the engine thrust, as obtained from the engine makers’ specification. To do this, accurate thrust data are essential and in certain cases these may not be readily available.In order to eliminate the possibility of systematic errors in the determination of engine thrust, a method has been developed whereby the drag at low Mach number can be measured directly,under such conditions that accurate knowledge of the engine performance is of minor importance. This method is satisfactory only on jetpropelled aircraft, since on conventional aircraft there are the added complications of propellers, slipstream, radiators and so on.The method has been used to determine the drag of the de Havilland D.H. 100 Vampire and has given good results. The drag determined from earlier tests by the usual procedure is found to be in good agreement with that given by the new method.

COMPARATIVE ACTION OF VARIOUS OESTROGENIC COMPOUNDS ON MOUSE VAGINAL SIALIC ACIDS (II)

1969 ◽  
Vol 62 (4) ◽  
pp. 663-670 ◽  
Author(s):  
Lars Carlborg
Keyword(s):  
Sialic Acid ◽  
Response Curve ◽  
Sialic Acids ◽  
Clear Cut ◽  
Suitable Parameter ◽  
Sufficient Degree ◽  
Comparative Action ◽  
Relative Potencies ◽  
Good Agreement

ABSTRACT Oestrogens administered in lower doses than necessary to induce full cornification of the mouse vagina induce mucification. It was shown previously that the degree of mucification could be estimated by quantitative determination of sialic acids. A suitable parameter for oestrogen assay was the measurement of vaginal sialic acid concentration which exhibited a clear cut dose response curve. Eleven assays of various oestrogens were performed with this method. Their estimated relative potencies were in good agreement with other routine oestrogen assays. A statistically sufficient degree of precision was found. The sensitivity was of the same order, or slightly higher, than the Allen-Doisy test.

Systematic errors in equilibrium composition of ternary liquid-liquid systems and their effect on the calculated number of theoretical stages of countercurrent extraction

1988 ◽  
Vol 53 (6) ◽  
pp. 1172-1180
Author(s):  
Ján Dojčanský ◽  
Soňa Bafrncová ◽  
Július Surový
Keyword(s):  
Equilibrium Composition ◽  
Systematic Errors ◽  
Liquid Equilibrium ◽  
Countercurrent Extraction ◽  
Liquid Systems ◽  
Equilibrium Concentrations ◽  
Line Slope ◽  
Tie Line ◽  
Calculated Number

The influence of magnitude of systematic errors in the determination of ternary liquid-liquid equilibrium concentrations on the accuracy of the calculated number of theoretical stages of countercurrent extraction is evaluated on using five hypothetical systems differing in the extent of mutual solubility of components, tie-line slope, and type of binodal curve.

An Automated Method for the Determination of Serum Calcium with Glyoxal Bis (2-Hydroxyanil)

1967 ◽  
Vol 13 (6) ◽  
pp. 515-520 ◽  
Author(s):  
Genevieve Farese ◽  
Janice L Schmidt ◽  
Milton Mager
Keyword(s):  
Serum Calcium ◽  
Automated Analysis ◽  
Automated Method ◽  
Good Agreement

Abstract A completely automated analysis is described for the determination of serum calcium with glyoxal bis (2-hydroxyanil) solution (GBHA). The method is simple and precise, and the data obtained are in good agreement with results obtained by the manual GBHA procedure.

Numerical evaluation of hydrodynamic characteristics of planing hulls by using a hybrid method

2021 ◽  
pp. 147509022199024
Author(s):  
Emre Kahramanoglu ◽  
Silvia Pennino ◽  
Huseyin Yilmaz
Keyword(s):  
Experimental Data ◽  
Hybrid Method ◽  
Design Stage ◽  
Hydrodynamic Characteristics ◽  
Calm Water ◽  
Preliminary Design Stage ◽  
Reduction Function ◽  
Hull Forms ◽  
Good Agreement

The hydrodynamic characteristics of the planing hulls in particular at the planing regime are completely different from the conventional hull forms and the determination of these characteristics is more complicated. In the present study, calm water hydrodynamic characteristics of planing hulls are investigated using a hybrid method. The hybrid method combines the dynamic trim and sinkage from the Zarnick approach with the Savitsky method in order to calculate the total resistance of the planing hull. Since the obtained dynamic trim and sinkage values by using the original Zarnick approach are not in good agreement with experimental data, an improvement is applied to the hybrid method using a reduction function proposed by Garme. The numerical results obtained by the hybrid and improved hybrid method are compared with each other and available experimental data. The results indicate that the improved hybrid method gives better results compared to the hybrid method, especially for the dynamic trim and resistance. Although the results have some discrepancies with experimental data in terms of resistance, trim and sinkage, the improved hybrid method becomes appealing particularly for the preliminary design stage of the planing hulls.

Contactless and Spatially‐Resolved Determination of Current‐Voltage Curves in Perovskite Solar Cells via Photoluminescence

Solar RRL ◽  
2021 ◽  
Author(s):  
Anh Dinh Bui ◽  
Md Arafat Mahmud ◽  
Naeimeh Mozaffari ◽  
Rabin Basnet ◽  
The Duong ◽  
...  
Keyword(s):  
Solar Cells ◽  
Perovskite Solar Cells ◽  
Spatially Resolved ◽  
Current Voltage
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