On-sky verification of the 6-h periodic basic angle variations of the Gaia satellite

2017 ◽  
Vol 12 (S330) ◽  
pp. 231-232
Author(s):  
Shilong Liao ◽  
Mario G. Lattanzi ◽  
Alberto Vecchiato ◽  
Zhaoxiang Qi ◽  
Mariateresa Crosta ◽  
...  
Keyword(s):  
Systematic Errors ◽  
Precise Determination ◽  
Accurate Estimation ◽  
A Value ◽  
Full Day ◽  
Astrometric Data

AbstractA Basic Angle (BA) of 106.5° separates the view directions of Gaia's two fields of view (FoV). A precise determination of the BA variations (BAV) is essential to guarantee a correct reconstruction of the global astrometric sphere, as residual systematic errors would result in, e.g., a bias in the parallaxes of the final Gaia catalog. The Basic Angle Monitoring (BAM) device, which provides a reliable and accurate estimation of BAV, shows that there exists a ~1 mas amplitude, 6-h period BA oscillation. It's essential to verify to what extent this signal is caused by real BAV, or is at least in part an effect of the BAM device itself. Here, we propose an astrometric on-sky approach to re-determine the 6-h periodic BAV. The results of this experiment, which treated a full day (17 Oct 2016) of Gaia astrometric data, recover a value for the 6-h oscillation of 1.856±0.857 mas. This is consistent, within the errors, with the BAM finding for that day.

Photoelectric-Yield Studies of c-Si/a-Si:H Interfaces

1995 ◽  
Vol 377 ◽  
Author(s):  
M. Sebastiani ◽  
L. Di Gaspare ◽  
C. Bittencourt ◽  
F. Evangelisti
Keyword(s):  
Valence Band ◽  
Precise Determination ◽  
Spectroscopy Study ◽  
Final State ◽  
A Value ◽  
Valence Band Discontinuity

ABSTRACTWe report the first yield spectroscopy study on well characterized c-Si/a-Si:H heterojunctions grown in situ under UHV conditions. We find that this spectroscopy, when operated in the constant final state mode, allows a direct and precise determination of the valence-band discontinuity at the interface. A value of δEv = 0.44 ± 0.02 eV was found for the discontinuity.

scholarly journals Technique for Measuring Spatial Distribution of the Surface Acoustic Wave Velocity in Metals

2016 ◽  
Vol 41 (4) ◽  
pp. 741-746 ◽  
Author(s):  
Oleh Mokryy ◽  
Oleksandr Tsyrulnyk
Keyword(s):  
Spatial Distribution ◽  
Spatial Resolution ◽  
Rayleigh Waves ◽  
High Spatial Resolution ◽  
Steel Specimen ◽  
Precise Determination ◽  
Local Velocity ◽  
A Value ◽  
Spatially Inhomogeneous

Abstract In this paper a possibility of determining a local velocity of the surface acoustic Rayleigh waves using a transducer, with the rigidly connected emitting and receiving parts, is considered. A problem on spatial resolution of such a transducer for investigation of inhomogeneous specimens is also examined. A high spatial resolution can be obtained due to the transducer displacement by a value less than the distance between the emitting and receiving parts. It is shown that in this case it is not necessary to measure the transducer displacement with a high accuracy for precise determination of the velocity. Such an effect is obtained through measuring the velocity of surface waves in one local region of the specimen with respect to the other. The criterion for optimal spatial resolution selection during spatially inhomogeneous specimens study is also proposed. The proposed criterion use is illustrated on the example of the determination of spatial distribution of the surface acoustic velocity in a steel specimen subjected to inhomogeneous plastic deformation.

scholarly journals PRECISE DETERMINATION OF THE CONDUCTIVITY EXPONENT OF 3D PERCOLATION USING "PERCOLA"

1996 ◽  
Vol 06 (06) ◽  
pp. 813-817 ◽  
Author(s):  
JEAN-MARIE NORMAND ◽  
HANS J. HERRMANN
Keyword(s):  
Three Dimensional ◽  
Precise Determination ◽  
Bond Percolation ◽  
Cpu Time ◽  
A Value ◽  
Correction To Scaling ◽  
Purpose Computer ◽  
Special Purpose Computer

Using 20 months of CPU time on our special purpose computer "Percola" we determined the exponent for the normal conductivity at the threshold of three-dimensional site and bond percolation. The extrapolation analysis taking into account the first correction to scaling gives a value of t/ν = 2.26±0.04 and a correction exponent ω around 1.4.

Localization Methods for Mobile Robots - A Review

2013 ◽  
Vol 837 ◽  
pp. 561-566 ◽  
Author(s):  
Ionel Conduraru ◽  
Ioan Doroftei ◽  
Alina Conduraru (Slătineanu)
Keyword(s):  
Mobile Robots ◽  
Large Scale ◽  
Precise Determination ◽  
Autonomous Mobile Robots ◽  
Accurate Estimation ◽  
Military Operations ◽  
Successful Operation ◽  
Robot System ◽  
Robot Position

In recent years more and more emphasis was placed on the idea of autonomous mobile robots, researches being constantly rising. Mobile robots have a large scale use in industry, military operations, exploration and other applications where human intervention is risky. The accurate estimation of the position is a key component for the successful operation for most of autonomous mobile robots. The localization of an autonomous robot system refers mainly to the precise determination of the coordinates where the system is present at a certain moment of time. In many applications, the orientation and an initial estimation of the robot position are known, being supplied directly or indirectly by the user or the supervisor. During the execution of the tasks, the robot must update this estimation using measurements from its sensors. This is known as local localization. Using only sensors that measure relative movements, the error in the pose estimation increases over time as errors are accumulated. Localization is a fundamental operation for navigating mobile robots

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.

Vitamin A Value of Plant Food Provitamin A - Evaluated by the Stable Isotope Technologies

2014 ◽  
Vol 84 (Supplement 1) ◽  
pp. 25-29 ◽  
Author(s):  
Guangwen Tang
Keyword(s):  
Stable Isotope ◽  
Vitamin A ◽  
Provitamin A ◽  
Animal Origin ◽  
Plant Food ◽  
Plant Foods ◽  
A Value ◽  
Provitamin A Carotenoids ◽  
Β Carotene

Humans need vitamin A and obtain essential vitamin A by conversion of plant foods rich in provitamin A and/or absorption of preformed vitamin A from foods of animal origin. The determination of the vitamin A value of plant foods rich in provitamin A is important but has challenges. The aim of this paper is to review the progress over last 80 years following the discovery on the conversion of β-carotene to vitamin A and the various techniques including stable isotope technologies that have been developed to determine vitamin A values of plant provitamin A (mainly β-carotene). These include applications from using radioactive β-carotene and vitamin A, depletion-repletion with vitamin A and β-carotene, and measuring postprandial chylomicron fractions after feeding a β-carotene rich diet, to using stable isotopes as tracers to follow the absorption and conversion of plant food provitamin A carotenoids (mainly β-carotene) in humans. These approaches have greatly promoted our understanding of the absorption and conversion of β-carotene to vitamin A. Stable isotope labeled plant foods are useful for determining the overall bioavailability of provitamin A carotenoids from specific foods. Locally obtained plant foods can provide vitamin A and prevent deficiency of vitamin A, a remaining worldwide concern.

PRECISE DETERMINATION OF THE IRRATIONAL PRE-FERRED INTERFACE ORIENTATION BY TEM

2010 ◽  
Vol 46 (4) ◽  
pp. 411-417 ◽  
Author(s):  
Yang MENG ◽  
Lin GU ◽  
Wenzheng ZHANG
Keyword(s):  
Precise Determination ◽  
Interface Orientation

Nauwkeurige methode voor de aanwasbepaling van het grondvlak met behulp van de Pressler-boor

1968 ◽  
Vol 12 ◽  
Author(s):  
R. Goossens
Keyword(s):  
Basal Area ◽  
Precise Determination ◽  
Maximum Diameter ◽  
Precise Method ◽  
Maximum Radius ◽  
The Core ◽  
Two Parameters

A precise method for the determination of the increment of the  basal area using the PressIer bore. Refering to  previous research showing that the basal area of the corsica pine could be  characterized by an ellips, we present in this paper a precise method for the  determination of the increment of the basal area. In this method we determine  the direction of the maximum diameter, we measure this diameter and we take a  core in one of the points of tangency of the caliper with the measured tree.  The determination of the diameter perpendicular to the maximum diameter  finishes the work wich is to be done in the forest. From the classical  measurements effectuated on the core and from the measured diameters we can  then determine the form (V) and the excentricity (e). Substituting these two  parameters in the formula 2 or 2', we can also calculate the error of a  radius measured on the core with respect to the representative radius, This  error with them allow us to correct the measured value of the minimum or the  maximum radius and we will be able to do a precise determination of the  increment.

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