Static shape determination and control for a large space antenna

1981 ◽  
Author(s):  
Connie Weeks
Keyword(s):  
Space Antenna ◽  
Large Space ◽  
Shape Determination ◽  
And Control

Static Shape Determination and Control of Large Space Structures: II. A Large Space Antenna

1984 ◽  
Vol 106 (4) ◽  
pp. 267-272 ◽  
Author(s):  
Connie J. Weeks
Keyword(s):  
Adjoint System ◽  
Performance Criteria ◽  
Space Structures ◽  
Space Antenna ◽  
Large Space ◽  
Solution Algorithms ◽  
Large Space Structures ◽  
Shape Determination ◽  
Control Forces ◽  
And Control

An integral operator approach is used to derive solutions to static shape determination and control problems associated with large space structures. Problem assumptions include a linear self-adjoint system model, observations and control forces at discrete points, and quadratic performance criteria for the comparison of estimates or control forces. Solutions reduce to the solution of linear equations of dimension on the order of the numbers of observations or control forces. Results are illustrated by simulations with a finite element model of a large space antenna. Modal expansions for terms in the solution algorithms are presented, using modes from the static or associated dynamic model. These expansions provide approximate solutions in the event that a closed form analytical solution to the system boundary value problem is not available.

Dynamics and control of a large space antenna

1984 ◽  
Vol 7 (1) ◽  
pp. 69-76 ◽  
Author(s):  
Shyh Jong Wang ◽  
Jonathan M. Cameron
Keyword(s):  
Space Antenna ◽  
Large Space ◽  
Dynamics And Control ◽  
And Control

Seti Space Missions

1997 ◽  
Vol 161 ◽  
pp. 761-776 ◽  
Author(s):  
Claudio Maccone
Keyword(s):  
Electromagnetic Waves ◽  
Space Missions ◽  
Gravitational Lens ◽  
The Sun ◽  
Space Antenna ◽  
Focal Distance ◽  
Large Space ◽  
The Earth ◽  
Space Antennas ◽  
New Space

AbstractSETI from space is currently envisaged in three ways: i) by large space antennas orbiting the Earth that could be used for both VLBI and SETI (VSOP and RadioAstron missions), ii) by a radiotelescope inside the Saha far side Moon crater and an Earth-link antenna on the Mare Smythii near side plain. Such SETIMOON mission would require no astronaut work since a Tether, deployed in Moon orbit until the two antennas landed softly, would also be the cable connecting them. Alternatively, a data relay satellite orbiting the Earth-Moon Lagrangian pointL2would avoid the Earthlink antenna, iii) by a large space antenna put at the foci of the Sun gravitational lens: 1) for electromagnetic waves, the minimal focal distance is 550 Astronomical Units (AU) or 14 times beyond Pluto. One could use the huge radio magnifications of sources aligned to the Sun and spacecraft; 2) for gravitational waves and neutrinos, the focus lies between 22.45 and 29.59 AU (Uranus and Neptune orbits), with a flight time of less than 30 years. Two new space missions, of SETI interest if ET’s use neutrinos for communications, are proposed.

scholarly journals Risk Analysis and Control Factors Based on Excavation of a Large Underground Subway Station under Construction

Symmetry ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1629
Author(s):  
Zhien Zhang ◽  
Mingli Huang ◽  
Baohua Wu
Keyword(s):  
Large Scale ◽  
Complex Structure ◽  
Subway Station ◽  
Multidimensional Space ◽  
Large Space ◽  
Control Factors ◽  
Underground Subway Station ◽  
Subway Stations ◽  
Under Construction ◽  
And Control

Considering the convenience of pedestrian transfer, reasonable structural stress and beautiful shape design, most subway stations adopt symmetrical design. At present, the new subway station is developing in the direction of a multidimensional space, as well as a large scale, and complex structure. Tunnel construction also presents unpredictability, coupling amplification and high risks. For example, a subway extension project involves construction, which would affect the normal use of the subway or damage its structure. Based on excavation of the largest underground subway station under construction in China, the Erligou station extension project (line 16 of Beijing Metro), and using theoretical analysis, numerical simulation, monitoring data, and other research methods, this paper quantitatively analyzes the risk of a large space station’s construction process on the adjacent existing station structure and track, as well as highlights key, high-risk sub-projects, or construction steps, combined with specific engineering measures to ensure safety during construction of a new station. The general rules concerning large space subway station construction are further summarized to provide reference for similar projects.

Sign in / Sign up

Export Citation Format

Share Document