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An introductory review of swarm technology for spacecraft on-orbit servicing

International Journal of Mechanical System Dynamics 2024年第1期4卷 3-21页

作者： El Ghali Asri Zheng h.zhu Department of Mechanical Engineering York UniversityTorontoOntarioCanada

This review paper presents a comprehensive evaluation and forward-looking perspective on the underexplored topic of servicing target objects using spacecraft *** targets can be known or unknown,cooperative or uncooperative,and pose significant challenges in modern space operations due to their inherent complexity and *** servicing space objects is vital for active debris removal and broader on-orbit servicing tasks such as satellite maintenance,repair,refueling,orbital assembly,and *** effort has been invested in the literature to explore the servicing of targets using a single *** its advantages and benefits,this paper expands the discussion to encompass a swarm approach to the *** review covers various single-spacecraft approaches and presents a critical examination of the existing,although limited,body of work dedicated to servicing orbital objects using multiple *** focus is also broadened to include some influential studies concerning the characterization,capture,and manipulation of physical objects by general multiagent systems,a subject with significant parallels to the core interest of this ***,this article also delves into the realm of simultaneous localization and mapping,highlighting its application within close-proximity operations in space,especially when dealing with unknown uncooperative *** attention is paid to the benefits that this field can receive from distributed multiagent ***,an exploration of the promising field of swarm robotics is presented,with an emphasis on its potential to revolutionize the servicing of orbital target ***,a survey of general research directly engaging swarms in the orbital context is *** review aims to bridge the knowledge gap and stimulate further research in the underexplored domain of servicing space targets with spacecraft swarms.

关键词： space robotics on-orbit servicing close-proximity operations guidance and navigation swarm robotics multiagent systems object capture and manipulation simultaneous localization and mapping

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Evaluation of E-sail parameters on central spacecraft attitude stability using a high-fidelity rigid–flexible coupling model

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Astrodynamics 2024年第2期8卷 271-284页

作者： Chonggang Du Zheng h.zhu Changqing Wang Aijun Li Tuanjie Li School of Electro-Mechanical Engineering Xidian UniversityXi’an 710071China Department of Mechanical Engineering York University4700 Keele StreetTorontoOntario M3J 1P3Canada School of Automation Northwestern Polytechnical UniversityXi’an 710129China

This study examines the impact of electric solar wind sail(E-sail)parameters on the attitude stability of E-sail’s central spacecraft by using a comprehensive rigid–flexible coupling dynamic *** this model,the nodal position finite element method is used to model the elastic deformation of the tethers through interconnected two-node tensile *** attitude dynamics of the central spacecraft is described using a natural coordinate *** rigid–flexible coupling between the central spacecraft and its flexible tethers is established using Lagrange *** research reveals the significant influences of parameters such as tether numbers,tether’s electric potential,and solar wind velocity on attitude ***,solar wind fluctuations and the distribution of electric potential on the main tethers considerably affect the attitude stability of the *** consistent management,the angular velocities of the spacecraft must remain at target ***,the attitude stability of a spacecraft has a pronounced dependence on the geometrical configuration of the E-sail,with axisymmetric E-sails proving to be more stable.

关键词： electric solar wind sail(E-sail) space tether nodal position finite element method(NPFEM) natural coordinate formulation (NCF) attitude stability

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A Preliminary Comparative Study on the Centering Algorithms for CassiniISS NAC Images

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Research in Astronomy and Astrophysics 2024年第10期24卷 58-65页

作者： T.Liang Q.-F.Zhang G.-M.Liu W.-h.zhu C.-S.Wang Department of Computer Science Jinan UniversityGuangzhou 510632China Sino-French Joint Laboratory for Astrometry Dynamics and Space ScienceJinan UniversityGuangzhou 510632China School of Computer Science Guangdong University of EducationGuangzhou 510303China

Obtaining high precision is an important consideration for astrometric studies using images from the Narrow Angle Camera(NAC)of the Cassini Imaging Science Subsystem(ISS).Selecting the best centering algorithm is key to enhancing astrometric *** this study,we compared the accuracy of five centering algorithms:Gaussian fitting,the modified moments method,and three point-spread function(PSF)fitting methods(effective PSF(ePSF),PSFEx,and extended PSF(x PSF)from the Cassini Imaging Central Laboratory for Operations(CICLOPS)).We assessed these algorithms using 70 ISS NAC star field images taken with CL1 and CL2 filters across different stellar *** ePSF method consistently demonstrated the highest accuracy,achieving precision below 0.03 pixels for stars of magnitude *** to the previously considered best,the modified moments method,the e PSF method improved overall accuracy by about 10%and 21%in the sample and line directions,***,the xPSF model provided by CICLOPS had lower precision than the ***,the ePSF exhibits an improvement in measurement precision of 23%and 17%in the sample and line directions,respectively,over the *** discrepancy might be attributed to the xPSF focusing on photometry rather than *** findings highlight the necessity of constructing PSF models specifically tailored for astrometric purposes in NAC images and provide guidance for enhancing astrometric measurements using these ISS NAC images.

关键词： methods:analytical techniques:image processing stars:imaging astrometry

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Parameter influence on electron collection efficiency of a bare electrodynamic tether

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Science China(Information Sciences) 2018年第2期61卷 24-35页

作者： Gangqiang LI Zheng h.zhu Department of Earth and Space Science and Engineering York University Department of Mechanical Engineering York University

This study develops a coupled multiphysics finite element method for the dynamic analysis of a bare flexible electrodynamic tether. Contrary to the existing methods, the new method discretizes and solves the orbital motion limited equation and the dynamic equation of an elastic flexible tether ***, the new method is verified via comparison with the existing methods in a straight tether ***, the number of tether elements, tether bending deformation, and two design parameters at the cathodic end affecting the electrical current are investigated. It is determined that the tether bending deformation and the two parameters i.e., the impedance ZT and ΦPWhave a significant impact on the electron collection efficiency of an electrodynamic tether system. The results indicate that the proposed method should be applied in the refined mission analysis.

关键词： multiphysics coupled finite element electrodynamic tether electron collection efficiency

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Orbital radius keeping of floating partial space elevator in cargo transposition

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Astrodynamics 2023年第3期7卷 259-269页

作者： Gefei Shi Zheng h.zhu School of Aeronautics and Astronautics Sun Yat-sen UniversityGuangzhou510275China Department of Mechanical Engineering York University4700 Keele StreetTorontoOntarioM3J 1P3Canada

A floating partial space elevator(PSE)is a PSE with a floating main *** work aims to keep the orbital radius of the main satellite of a floating PSE in cargo transposition without the use of thrusts.A six-degree-of-freedom two-piece dumbbell model was built to analyze the dynamics of a floating *** adjusting the climber’s moving speed and rolling of the end body,the main satellite’s orbital radius can be kept.A novel control strategy using a proportional shrinking horizon model predictive control law containing a self-stability modified law is proposed to stabilize both the orbital and libration states to regulate the speed of only the *** results validated the proposed control *** system provides a successful approach to the desired equilibrium by the end of the transposition.

关键词： floating partial space elevator(PSE) self-stability modified law shrinking horizon model predictive control

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Libration and end body swing stabilization of a parallel partial space elevator system

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Chinese Journal of Aeronautics 2021年第3期34卷 187-199页

作者： Gefei ShI Gangqiang LI Zheng h.zhu School of Aeronautics and Astronautics Sun Yat-Sen UniversityGuangzhou 510275China Department of Mechanical Engineering York UniversityTorontoOntario M3J 1P3Canada

This paper studies the libration and stabilization of a parallel partial space elevator system in circular orbits. The system is made up of two paralleled partial space elevators, each of which consists of one main satellite, one end body and a climber moving along the tether between *** libration characteristics of the elevator are studied through numerical analysis by a new dynamic model, and a novel control strategy is proposed to stabilize the swing of the end body by projecting the climber speeds only. Optimal control method is used to implement the new control strategy in the case where the climbers move in opposite direction. The simulation results validate the effectiveness of the proposed control strategy whose application will neither sacrifice the transport efficiency nor exacerbate libration significantly.

关键词： Libration stabilization Nonlinear dynamics Optimal control Parallel partial space elevator Space tether

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Improving the performance of structure-embedded acoustic lenses via gradient-index local inhomogeneities

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International Journal of Smart and Nano Materials 2015年第1期6卷 1-13页

作者： h.zhu F.Semperlotti Department of Aerospace and Mechanical Engineering University of Notre DameNotre DameIndiana 46556USA

We investigate the use of graded inhomogeneities in order to enhance the focusing and collimation performance of structure-embedded acoustic metamaterial *** type of inhomogeneity exploited in this study consists in axial symmetric exponential-like gradients of either material or geometric properties that create gradient-index inclusions able to bend and redirect propagating *** particular,we exploit the concept of gradient index inclusions to achieve focusing and collimation of ultrasonic beams created by embedded drop-channel lenses in both bulk and thin-walled *** the latter,the implementation is possible thanks to geometric exponential tapers known as Acoustic Black holes(ABh).ABh tapers allow accurate control of the characteristics of the acoustic beam emanating from the lens channel which in the conventional design is severely affected by *** concept of beam control via graded inclusions is numerically illustrated and validated by using a combination of methodologies including geometric acoustics,finite difference time domain,and finite element methods.

关键词： acoustic lens acoustic black hole gradient index inhomogeneity drop-channel acoustic metamaterials

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Dynamics and de-spin control of massive target by single tethered space tug

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Chinese Journal of Aeronautics 2019年第3期32卷 653-659页

作者： Junjie KANG Zheng h.zhu Wei WANG Changqing WANG Aijun LI Department of Earth and Space Science and Engineering York University School of Automation Northwestern Polytechnical University Department of Mechanical Engineering York University

This paper investigates the dynamics and de-spin control of a massive target by a single tethered space tug in the post-capture phase. The dynamic model of the tethered system is derived and simplified to a dimensionless form. Further, a decoupled PD controller is proposed, and the local stability of the controller is analyzed by linearization technique. Parametric studies of the dynamics and de-spin control of a massive target are conducted to characterize the dynamic process of de-spin with the proposed control law. It is shown that the massive target can be de-span by a single and small space tug with limited thrust within finite time. The thrust tangent with the tether de-spins the target while the thrust normal to the tether prevents the tether from winding up the target. The tether length has a positive contribution to the de-spin of a target. The longer tether leads to a faster de-spin process.

关键词： De-spin Dynamics PD control Space tethers Tethered tug

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Effectiveness of two different acupuncture strategies in patients with vulvodynia Study protocol for a pilot pragmatic controlled trial

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Journal of Integrative Medicine 2018年第6期16卷 384-389页

作者： Arthur Yin Fan Sarah F.Alemi Yingping h.zhu Sudaba Rahimi hui Wei haihe Tian Deguang he Changzhen Gong Guanhu Yang Chong he hui Ouyang American Traditional Chinese Medicine Association ViennaVA 22182USA McLean Center for Complementary and Alternative Medicine PLC.ViennaVA 22182USA

Background： Vulvodynia, or vulvar pain, is a common condition in women; however, there are few evidence-based clinical trials evaluating nonpharmacological therapies for this condition. Acupuncture is one complementary and integrative medicine therapy used by some patients with vulvodynia. This study evaluates two different acupuncture strategies for the treatment of vulvodynia and aims to evalu- ate whether either of the acupuncture protocols reduces vulvar pain, pain duration or pain with inter- course. The study also examines how long the effect of acupuncture lasts in women with vulvodynia. Methods/design： The study is designed as a randomized controlled trial, focused on two acupuncture protocols. Fifty-one patients who have had vulvodynia for more than 3 months will be recruited. Among them, 34 patients will be randomized into Groups la and 1b; those who are unwilling to receive acupuncture will be recruited into the standard care group （Group 2）. Patients in Group la will have acupuncture focused on the points in the pudendal nerve distribution area, while patients in Group lb will receive acupuncture focused on traditional （distal） meridian points. Patients in Group 2 will receive routine conventional treatments, such as using pain medications, local injections and physical therapies or other nonsurgical procedures. Acupuncture will last 45 min per session, once or twice a week for 6 weeks. The primary outcome measurement will be objective pain intensity, using the cotton swab test. The secondary outcome measurement will be subjective patient self-reported pain intensity, which will be conducted before cotton swab test. Pain intensities will be measured by an 11-point Numeric Pain Rating Scale. Pain duration and pain score during intercourse are recorded. Local muscle tension, tender- ness and trigger points （Ashi points） are also recorded. All measurements will be recorded at baseline （before the treatment）, at the end of each week during treatment and at t

关键词： Acupuncture Vulvodynia Meridian points Pudendal nerve Study protocol

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Raman Scattering from an Individual Graphite Tubular Cone

Raman Scattering from an Individual Graphite Tubular Cone

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第十三届全国光散射学术会议

作者： P.h.Tan h.zhu G.Y.Zhang E.G.Wang State Key Laboratory for Superlattices and Microstructures Institute of SemiconductorsChinese Academy of Sciences State Key Laboratory for Surface Physics Institute of PhysicsChinese Academy of Sciences

＜正＞Carbon has the wide variety of forms,such as diamond,graphite,fullerenes and *** materials play an important role in the applications of field emission displays,microwave amplifiers,transistors,hydrogen storage,etc.[1]Recently,so-called tubular graphite cones（TGCs）are synthesized on an iron needle using a chemical vapor deposition

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