Symmetric oscillations of charged gyrostat in weakly elliptical orbit with small inclination

2016 ◽  
Vol 85 (3) ◽  
pp. 1919-1927 ◽  
Author(s):  
A. A. Tikhonov ◽  
V. N. Tkhai
Keyword(s):  
Elliptical Orbit ◽  
Weakly Elliptical Orbit ◽  
Small Inclination

scholarly journals Orbit Decomposition Method for Rotordynamic Coefficients Identification of Annular Seals

2021 ◽  
Vol 11 (9) ◽  
pp. 4237
Author(s):  
Mingjie Zhang ◽  
Jiangang Yang ◽  
Wanfu Zhang ◽  
Qianlei Gu
Keyword(s):  
Circular Orbit ◽  
Present Method ◽  
Decomposition Method ◽  
Parameter Analysis ◽  
Elliptical Orbit ◽  
Computational Time ◽  
Solution Technique ◽  
Rotordynamic Coefficients ◽  
Cfd Method ◽  
Annular Seals

The elliptical orbit whirl model is widely used to identify the frequency-dependent rotordynamic coefficients of annular seals. The existing solution technique of an elliptical orbit whirl model is the transient computational fluid dynamics (CFD) method. Its computational time is very long. For rapid computation, this paper proposes the orbit decomposition method. The elliptical whirl orbit is decomposed into the forward and backward circular whirl orbits. Under small perturbation circumstances, the fluid-induced forces of the elliptical orbit model can be obtained by the linear superposition of the fluid-induced forces arising from the two decomposed circular orbit models. Due to that the fluid-induced forces of circular orbit, the model can be calculated with the steady CFD method, and the transient computations can be replaced with steady ones when calculating the elliptical orbit whirl model. The computational time is significantly reduced. To validate the present method, its rotordynamic results are compared with those of the transient CFD method and experimental data. Comparisons show that the present method can accurately calculate the rotordynamic coefficients. Elliptical orbit parameter analysis reveals that the present method is valid when the whirl amplitude is less than 20% of seal clearance. The effect of ellipticity on rotordynamic coefficients can be ignored.

On the Deployment of a Tether from an Elliptical Orbit

1998 ◽  
Vol 46 (2) ◽  
pp. 119-133 ◽  
Author(s):  
M. Ruiz ◽  
J. Peláez
Keyword(s):  
Elliptical Orbit

Elliptical Orbit of Asteroid 1986 QE1

1989 ◽  
Vol 12 ◽  
pp. 21-24
Author(s):  
H. Debehogne ◽  
L.E. Machado ◽  
S. Vaz ◽  
E.R. Netto
Keyword(s):  
Photographic Plate ◽  
Elliptical Orbit ◽  
Orbital Elements ◽  
European Southern Observatory ◽  
Geocentric Distance ◽  
Before And After

We present the orbital elements of asteroid QE1 (pro visional designation) identified in august 26, 1986, on a photographic plate obtained at the GPO telescope of the European Southern Observatory (ESO), La Silla, Chile, as well as the positions (AR and Dec) referred to 1950.0. Residues (0 - C) of the position in AR and Dec of the asteroid are given, both before and after applying variation in the geocentric distance.

scholarly journals A Meshfree Method for Heat Explosion Problems with Natural Convection in Inclined Porous Media

2018 ◽  
Vol 241 ◽  
pp. 01019 ◽  
Author(s):  
Abdoulhafar Halassi ◽  
Youssef Joundy ◽  
Loubna Salhi ◽  
Ahmed Taik
Keyword(s):  
Porous Media ◽  
Natural Convection ◽  
Vertical Direction ◽  
Meshfree Method ◽  
Boussinesq Approximation ◽  
Complex Behaviour ◽  
Meshless Collocation ◽  
Darcy Equations ◽  
Small Inclination ◽  
Good Agreement

This paper investigates the interaction between natural convection and heat explosion in porous media. A meshless collocation method based on multiquadric radial basis functions has been applied to study the problem in an inclined two-dimensional porous media. The governing equations consist of coupling the Darcy equations in the Boussinesq approximation of low density variations to the heat equation with a nonlinear chemical source term. The numerical results obtained are in good agreement with some previous studies that consider the vertical direction. A complex behaviour of solutions is observed, including periodic and aperiodic oscillations. We have shown that a small inclination of the container stabilizes the reactive fluid and can prevent thermal explosion.

scholarly journals Strategies of traversing obstacles and the simulation for a forestry chassis

2018 ◽  
Vol 15 (3) ◽  
pp. 172988141877390 ◽  
Author(s):  
Yue Zhu ◽  
Jiangming Kan ◽  
Wenbin Li ◽  
Feng Kang
Keyword(s):  
Multibody Dynamics ◽  
Inclination Angle ◽  
Degrees Of Freedom ◽  
Ride Comfort ◽  
Hydraulic Cylinder ◽  
Single Side ◽  
Simulation Results ◽  
Maximum Inclination ◽  
Three Degrees Of Freedom ◽  
Small Inclination

As to the complicated terrain in forest, forestry chassis with an articulated body with three degrees of freedom and installed luffing wheel-legs (FC-3DOF&LW) is a novel chassis that can surmount obstacles. In addition, the rear frame of FC-3DOF&LW is regarded as the platform to carry equipment. Small inclination angle for rear frame contributes to stability and ride comfort. This article describes the strategy of traversing obstacles and simulation for FC-3DOF&LW that drives in forest terrain. First, key structures of FC-3DOF&LW are briefly introduced, which include articulated structure with three degrees of freedom and luffing wheel-leg. Based on the sketch of luffing wheel-leg, the movement range of luffing wheel-leg is obtained by hydraulic cylinder operation. Second, the strategy of crossing obstacles that are simplified three models of terrain is presented, and the simulation for surmounting obstacles is constructed in multibody dynamics software. The simulation results demonstrate that the inclination angle of rear frame is 18° when slope is 30°. A maximum 12° decrease of inclination angle for rear frame can be acquired when luffing wheel-legs are applied. For traversing obstacles with both sides, the maximum inclination angle of rear frame is about 1.2° and is only 3° for traversing obstacles with single side.

scholarly journals Spatial and Temporal Sampling of Polar Regions from Two-Satellite System on Molniya Orbit

2011 ◽  
Vol 28 (8) ◽  
pp. 977-992 ◽  
Author(s):  
Alexander P. Trishchenko ◽  
Louis Garand
Keyword(s):  
Temporal Resolution ◽  
Arctic Region ◽  
Satellite System ◽  
Elliptical Orbit ◽  
High Temporal Resolution ◽  
Polar Regions ◽  
Temporal Sampling ◽  
Continuous Coverage ◽  
Depth Analysis

Abstract There has been a significant increase of interest in the building of a comprehensive Arctic observing system in recent years to properly and timely track the environmental and climate processes in this vast region. In this regard, a satellite observing system on highly elliptical orbit (HEO) with 12-h period (Molniya type) is of particular interest, because it enables continuous coverage of the entire Arctic region (58°–90°N) from a constellation of two satellites. Canada is currently proposing to operate such a constellation by 2017. Extending the pioneering study of S. Q. Kidder and T. H. Vonder Haar, this paper presents in-depth analysis of spatiotemporal sampling properties of the imagery from this system. This paper also discusses challenges and advantages of this orbit for various applications that require high temporal resolution and angular sampling.

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