Novel Surface Design of Deployable Reflector Antenna Based on Polar Scissor Structures

Space-deployable mechanisms can be used as supporting structures for large-diameter antennas in space engineering.This study proposes a novel method for constructing the surface design of space reflector antennas based on polar scissor units.The concurrency and deployability equations of the space scissor unit with definite surface constraints are derived using the rod and vector methods.Constraint equations of the spatial transformation for space n-edge polar scissor units are summarized.A new closed-loop deployable structure,called the polar scissor deployable antenna(PSDA),is designed by combining planar polar scissor units with spatial polar scissor units.The overconstrained problem is solved by releasing the curve constraint that locates at the end-point of the planar scissor mechanism.Kinematics simulation and error analysis are performed.The results show that the PSDA can effectively fit the paraboloid of revolution.Finally,deployment experiments verify the validity and feasibility of the proposed design method,which provides a new idea for the construction of large space-reflector antennas.

一种新型3-CRU并联机构的动力学建模

3-CRU平动并联机构具有3条CRU支链组,具有三个运动方向上的平动特性,对于目前多数并联机构需要较少自由度这一现状以及在生产中的实际情况,本文根据广发的调查取证,设计并验证了一种全新的3-CRU平动并联机械手,在对机构进位置和速度分析的基础上,得到新机构的第一阶影响系数矩阵,继而采用虚功法建立新型3-CRU平动并联机构运动平台的动力学模型,为精密机构平台的精度划分提供帮助。

Design and application of solar sailing: A review on key technologies

Solar sail technology has been proposed and developed for space explorations with advantages of low launch cost,no-propellant consumption,and continuous thrust,which has great potentials in earth polar detection,interstellar explorations and etc.The development of solar sail has made significant progress in structural design,manufacturing,materials,orbit transfer,and stability control in the past few decades,which makes meaningful contributions to astronomy,physics,and aerospace science.Technological breakthroughs of Solar Radiation Pressure(SRP)propulsion and interstellar transfer have been achieved in current solar sail missions.However,there are still many challenges and problems need to be solved.This paper attempts to summarize the research schemes and potential applications of solar sailing in space missions from the viewpoint of key technologies,so as to provide an overall perspective for researchers in this field.Analyses of the key technologies of solar sailing system design are provided.Finally,challenges and prospective development of solar sailing are discussed.

Analytical solution of a hyperbolic partial differential equation and its application

Purpose-The purpose of this paper is to investigate the analytical solution of a hyperbolic partial differential equation(PDE)and its application.Design/methodology/approach-The change of variables and the method of successive approximations are introduced.The Volterra transformation and boundary control scheme are adopted in the analysis of the reaction-diffusion system.Findings-A detailed and complete calculation process of the analytical solution of hyperbolic PDE(1)-(3)is given.Based on the Volterra transformation,a reaction-diffusion system is controlled by boundary control.Originality/value-The introduced approach is interesting for the solution of hyperbolic PDE and boundary control of the reaction-diffusion system.

Distributed learning particle swarm optimizer for global optimization of multimodal problems

Particle swarm optimizer （PSO） is an effective tool for solving many optimization problems. However, it may easily get trapped into local optimum when solving com- plex multimodal nonseparable problems. This paper presents a novel algorithm called distributed learning particle swarm optimizer （DLPSO） to solve multimodal nonseparable prob- lems. The strategy for DLPSO is to extract good vector infor- mation from local vectors which are distributed around the search space and then to form a new vector which can jump out of local optima and will be optimized further. Experimen- tal studies on a set of test functions show that DLPSO ex- hibits better performance in solving optimization problems with few interactions between variables than several other peer algorithms.

Control and synchronization of a hyperchaotic finance system via single controller scheme

Purpose–The purpose of this paper is to study the control and synchronization of the hyperchaotic finance system.Design/methodology/approach–A single controller scheme is introduced.The Routh-Hurwitz criteria and the structure of solution of first-order linear differential equations are adopted in analysis of control and synchronization.Findings–Two single controllers are designed and added to the new hyperchaotic finance system.The stability of the hyperchaotic finance system at its zero equilibrium point is guaranteed by applying the appropriate single controller signal based on Routh-Hurwitz criteria.Another effective controller is also designed for the global asymptotic synchronization on the hyperchaotic finance system based on the structure of solution of first-order linear differential equations.Numerical simulations are demonstrated to verify the effectiveness of the proposed single controller scheme.Originality/value–The introduced approach is interesting for control and synchronization the hyperchaotic finance system.