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Article
Publication date: 16 March 2020

Ran Sun, Aidang Shan, Chengxi Zhang and Qingxian Jia

This paper aims to investigate the feasibility of using the combination of Lorentz force and aerodynamic force as a propellantless control method for spacecraft formation.

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Abstract

Purpose

This paper aims to investigate the feasibility of using the combination of Lorentz force and aerodynamic force as a propellantless control method for spacecraft formation.

Design/methodology/approach

It is assumed that each spacecraft is equipped with several large flat plates, which can rotate to produce aerodynamic force. Lorentz force can be achieved by modulating spacecraft’s electrostatic charge. An adaptive output feedback controller is designed based on a sliding mode observer to account for unknown uncertainties and the absence of relative velocity measurements. Aiming at distributing the control input, an optimal control allocation method is proposed to calculate the electrostatic charge of the Lorentz spacecraft and control commands for the atmospheric-based actuators.

Findings

Numerical examples are provided to demonstrate the effectiveness of the proposed control strategy in the presence of J2 perturbations. Simulation results show that relative motion in a formation can be precisely controlled by the proposed propellantless control method under uncertainties and unavailability of velocity measurements.

Research limitations/implications

The controllability of the system is not theoretically investigated in the current work.

Practical implications

The proposed control method introduced in this paper can be applied for small satellites formation in low Earth orbit.

Originality/value

The main contribution of the paper is the proposal of the propellantless control approach for satellite formation using the combination of Lorentz force and aerodynamic force, which can eliminate the requirement of the propulsion system.

Details

Aircraft Engineering and Aerospace Technology, vol. 92 no. 4
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 16 October 2007

Robert G. Tian and Yan Wu

The purpose of this paper is to examine the construction of virtual community identities among Chinese internet users and their motivation for lurking, posting or flaming.

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Abstract

Purpose

The purpose of this paper is to examine the construction of virtual community identities among Chinese internet users and their motivation for lurking, posting or flaming.

Design/methodology/approach

Taking Qiangguo Luntan as an online study site the authors apply an ethnographic approach for the research, a method that is becoming more and more favourable by scholars in study virtual communities. The data gathered are mainly through participant observation and in‐depth interviews.

Findings

The findings suggest that internet bulletin boards enable ordinary Chinese to have their identities as politically activated citizens constructed in cyberspace. A consistent enthusiasm for political participation can be found in user's pennames, signature files, political clusters, and online behaviours.

Originality/value

This is an original case study.

Details

Multicultural Education & Technology Journal, vol. 1 no. 4
Type: Research Article
ISSN: 1750-497X

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