Determination of the extent of ion thruster efflux deposition on spacecraft surfaces from the SERT II flight thermal data

1975 ◽  
Author(s):  
N. STEVENS
Keyword(s):  
Ion Thruster ◽  
Thermal Data

scholarly journals AUTOMATIC MAPPING OF GLACIER BASED ON SAR IMAGERY BY BENEFITS OF FREELY OPTICAL AND THERMAL DATA

2015 ◽  
Vol XL-3/W2 ◽  
pp. 47-51
Author(s):  
L. Fang ◽  
L. Hoegner ◽  
U. Stilla
Keyword(s):  
Land Surface ◽  
Low Resolution ◽  
Glacier Surface ◽  
Thermal Data ◽  
Automatic Mapping ◽  
Resources Evaluation ◽  
Sar Imagery ◽  
Normalized Difference Snow Index ◽  
Occurrence Matrix

For many research applications like water resources evaluation, determination of glacier specific changes, and for calculation of the past and future contribution of glaciers to sea-level change, parameters about the size and spatial distribution of glaciers is crucial. In this paper, an automatic method for determination of glacier surface area using single track high resolution TerraSAR-X imagery by benefits of low resolution optical and thermal data is presented. Based on the normalized difference snow index (NDSI) and land surface temperature (LST) map generated from optical and thermal data combined with a surface slope data, a low resolution binary mask was derived used for the supervised classification of glacier using SAR imagery. Then, a set of suitable features is derived from the SAR intensity image, such as the texture information generated based on the gray level co-occurrence matrix (GLCM), and the intensity values. With these features, the glacier surface is discriminated from the background by Random Forests (RF) method.

scholarly journals Determination of the force transmitted by an ion thruster plasma plume to an orbital object

2016 ◽  
Vol 119 ◽  
pp. 241-251 ◽  
Author(s):  
A. Alpatov ◽  
F. Cichocki ◽  
A. Fokov ◽  
S. Khoroshylov ◽  
M. Merino ◽  
...  
Keyword(s):  
Plasma Plume ◽  
Ion Thruster

Solidification Behavior of Fe-Base Amorphous Alloys during Twin-Roll Strip Casting

2006 ◽  
Vol 15-17 ◽  
pp. 433-438
Author(s):  
Yoon S. Oh ◽  
Jung G. Lee ◽  
Choong Nyun Paul Kim ◽  
Nack J. Kim
Keyword(s):  
Amorphous Alloys ◽  
Strip Casting ◽  
Nucleation Theory ◽  
Solidification Behavior ◽  
Bulk Amorphous Alloys ◽  
Glass Forming ◽  
Thermal Data ◽  
Cct Diagrams ◽  
Twin Roll

Solidification behavior of two Fe-base amorphous alloys during twin-roll strip casting has been investigated in the present study. Continuous cooling transformation (CCT) diagrams of both alloys were calculated using the heterogeneous nucleation theory coupled with thermal data obtained during cooling. Cooling sequence during twin-roll strip casting was also simulated. These were used for the determination of the optimum twin-roll strip casting conditions at which desirable solidification behavior could be achieved. It shows that twin-roll strip casting can continuously fabricate sheet product of Fe-base bulk amorphous alloys, despite their higher liquidus temperatures and larger differences between liquidus and glass transition temperatures (Tg) than those of other easier glass-forming bulk amorphous alloys.

Microstructural Characterization and Mathematical Modeling for Determination of Volume Fraction of Eutectoid Mixture of the Cu-8.5wt% Sn Alloy Obtained by Unidirectional Upward Solidification

2020 ◽  
Vol 1012 ◽  
pp. 302-307
Author(s):  
Ricardo Aparecido da Cruz ◽  
Givanildo Alves dos Santos ◽  
Mauricio Silva Nascimento ◽  
Carlos Frajuca ◽  
Francisco Yastami Nakamoto ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Volume Fraction ◽  
Microstructural Characterization ◽  
Solidification Time ◽  
Fourier Number ◽  
Proposed Model ◽  
Thermal Data ◽  
Order Of Magnitude

The Cu-8.5wt % Sn alloy presents an extensive microsegregation during its solidification. That microsegregation results in the formation of a eutectoid mixture, which is detrimental to subsequent forming processes. This study deals with the influence of solidification time and cooling rate on the microstructure of that alloy. The unidirectional solidification technique allowed the acquisition of thermal data. The optical microscopy enabled the microstructural characterization of the material, the measurement of dendrite arm spacings and the quantification of the volume fraction of the eutectoid mixture. A semi-analytical mathematical model was proposed to estimate the volume fraction of the eutectoid mixture. The model expresses the volume fraction as an implicit function of the Fourier number. The results showed that the microstructure is dendritic and that the characteristic spacings increase with the solidification time between the liquidus and the peritectic temperatures. The data also showed that for higher cooling rates the dendrite arm spacings are smaller and that there is a tendency for the volume fraction of eutectoid mixture in the columnar zone to increase with the Fourier number and to decrease with the cooling rate. The proposed model allowed obtaining values of volume fraction with the same order of magnitude of the experimental data, but with behavior tendency opposite to that observed.

Determination of a force transmitted by a plume of an ion thruster to an orbital object

2016 ◽  
Vol 22 (1(98)) ◽  
pp. 52-63
Author(s):  
A.P. Alpatov ◽  
◽  
A.E. Zakrzhevskii ◽  
M. Merino ◽  
A.A. Fokov ◽  
...  
Keyword(s):  
Ion Thruster

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

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.

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