scholarly journals The Lorentzian oscillator group as a geodesic orbit space

2012 ◽  
Vol 53 (10) ◽  
pp. 103510 ◽  
Author(s):  
W. Batat ◽  
P. M. Gadea ◽  
J. A. Oubiña
Keyword(s):  
Orbit Space ◽  
Oscillator Group ◽  
Geodesic Orbit Space

scholarly journals Homogeneous geodesics in pseudo-Riemannian nilmanifolds

2016 ◽  
Vol 16 (2) ◽  
Author(s):  
Viviana del Barco
Keyword(s):  
Lie Groups ◽  
Lie Algebra ◽  
Orbit Space ◽  
Nilpotent Lie Groups ◽  
Invariant Metric ◽  
Natural Parameter ◽  
Geodesic Orbit Space ◽  
Affine Parameter ◽  
Homogeneous Geodesics

AbstractWe study the geodesic orbit property for nilpotent Lie groups N endowed with a pseudo-Riemannian left-invariant metric. We consider this property with respect to different groups acting by isometries. When N acts on itself by left-translations we show that it is a geodesic orbit space if and only if the metric is bi-invariant. Assuming N is 2-step nilpotent and with non-degenerate center we give algebraic conditions on the Lie algebra n of N which imply that every geodesic is the orbit of a one-parameter subgroup of N.Auto(N). In addition we present an example of an almost g.o. space such that for null homogeneous geodesics, the natural parameter of the orbit is not always the affine parameter of the geodesic.

Electromagnetic-launch-based method for cost-efficient space debris removal

2020 ◽  
Vol 29 (1) ◽  
pp. 94-106
Author(s):  
Chongyuan Hou ◽  
Yuan Yang ◽  
Yikang Yang ◽  
Kaizhong Yang ◽  
Xiao Zhang ◽  
...  
Keyword(s):  
Space Debris ◽  
Orbit Space ◽  
Low Earth Orbit ◽  
Research Progress ◽  
Area Of Interest ◽  
Electromagnetic Launch ◽  
Debris Removal ◽  
Significant Research ◽  
Electromagnetic Launcher ◽  
Cost Efficient

AbstractThe increase in space debris orbiting Earth is a critical problem for future space missions. Space debris removal has thus become an area of interest, and significant research progress is being made in this field. However, the exorbitant cost of space debris removal missions is a major concern for commercial space companies. We therefore propose the debris removal using electromagnetic launcher (DREL) system, a ground-based electromagnetic launch system (railgun), for space debris removal missions. The DREL system has three components: a ground-based electromagnetic launcher (GEML), suborbital vehicle (SOV), and mass of micrometer-scale dust (MSD) particles. The average cost of removing a piece of low-earth orbit space debris using DREL was found to be approximately USD 160,000. The DREL method is thus shown to be economical; the total cost to remove more than 2,000 pieces of debris in a cluster was only approximately USD 400 million, compared to the millions of dollars required to remove just one or two pieces of debris using a conventional space debris removal mission. By using DREL, the cost of entering space is negligible, thereby enabling countries to remove their space debris in an affordable manner.

Atomic Oxygen Resistant Polysiloxane Coatings for Low Earth Orbit Space Structures

2015 ◽  
Vol 830-831 ◽  
pp. 699-702 ◽  
Author(s):  
G.N. Arjun ◽  
T.L. Lincy ◽  
T.S. Sajitha ◽  
S. Bhuvaneshwari ◽  
Thomas Deepthi ◽  
...  
Keyword(s):  
Reaction Time ◽  
Surface Morphology ◽  
Mass Loss ◽  
Atomic Oxygen ◽  
Thermo Gravimetric Analysis ◽  
Orbit Space ◽  
Solid Content ◽  
Low Earth Orbit ◽  
Gravimetric Analysis ◽  
Coating Materials

Polysiloxane resin copolymer was synthesized through acid catalyzed hydrolysis of methyl triethoxysilane (MTEOS) and diethoxytetramethyldisiloxane (DEOTMDS). The effect of reaction time on the properties of the polymer was studied and this copolymer was characterized by GPC, 29Si NMR, IR, TGA, viscosity, refractive index, specific gravity and solid content. 29Si NMR and IR showed characteristic signals of Si-O-Si linkage which confirmed the formation of the polymer. GPC and solid content analysis showed an increasing trend in molecular weight with reaction time. Thermo gravimetric analysis showed that the polymer was thermally stable upto ≈ 260°C and all the polymers gave a ceramic residue in the range of 77-80% at 900°C. Siloxane prepared inhouse and methyl phenyl silsequioxane (control) were used as coating materials and atomic oxygen (AO) resistance was evaluated on Al-Kapton, carbon polyimide composite and glass polyimide composite. The mass loss and surface morphology of the coated samples were measured at different time intervals. It is observed that mass loss of polysiloxane coated samples was very less, compared to coated control samples. The morphology of all the samples were studied using FESEM. Erosion kinetics and surface morphology investigation indicate that the polysiloxane coating possesses excellent AO resistance, and displays better cracking resistance on AO exposure.

On the cohomology of orbit space of free ℤ p -actions on lens spaces

2007 ◽  
Vol 117 (3) ◽  
pp. 287-292 ◽  
Author(s):  
Hemant Kumar Singh ◽  
Tej Bahadur Singh
Keyword(s):  
Orbit Space ◽  
Lens Spaces

Study on Dynamic IR Image Generation of Space Target

2014 ◽  
Vol 1044-1045 ◽  
pp. 1343-1348
Author(s):  
Wu Can He ◽  
Shou Yi Liao ◽  
Zuo Yu Zhang ◽  
He Xin Zhang
Keyword(s):  
Infrared Imaging ◽  
Three Dimensional ◽  
Orbit Space ◽  
Guidance System ◽  
Image Generation ◽  
Hardware In The Loop ◽  
Imaging Guidance ◽  
Infrared Star ◽  
Objective Basis ◽  
Space Target

Dynamic IR image generation of space target is one of the key technologies in hardware in the loop simulation for the infrared imaging guidance system. The three-dimensional entity model is created in the Creator, Sinda/Fluint is used to analyze each part of dynamic infrared radiation characteristics from on-orbit Space Target, on the basis of the LRS infrared star catalogues, celestial background modeling is built. In Vega, the dynamic IR image of space target is generated. The simulation results show that the dynamic IR image of Space Target provide the important objective basis for the hardware in the loop simulation for the infrared imaging guidance system.

2D ELASTICITY TENSOR INVARIANTS, INVARIANTS DEFINITE POSITIVE CRITERIA

2021 ◽  
Vol 10 (8) ◽  
pp. 2999-3012
Author(s):  
K. Atchonouglo ◽  
G. de Saxcé ◽  
M. Ban
Keyword(s):  
Group Action ◽  
Linear Elasticity ◽  
Orbit Space ◽  
Rotation Group ◽  
Elasticity Tensor ◽  
Tensor Invariants ◽  
Material Classification ◽  
The One ◽  
2D Elasticity ◽  
Space Description

In this paper, we constructed relationships with the differents 2D elasticity tensor invariants. Indeed, let ${\bf A}$ be a 2D elasticity tensor. Rotation group action leads to a pair of Lax in linear elasticity. This pair of Lax leads to five independent invariants chosen among six. The definite positive criteria are established with the determined invariants. We believe that this approach finds interesting applications, as in the one of elastic material classification or approaches in orbit space description.

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