Space manipulators have attracted much attention due to their implications in on-orbit servicing in recent years. Air bearing based support equipment is widely used for ground test to offset the effect of gravity. However, an air bearing support introduces a new problem caused by additional inertial and mass properties. Additional mass and inertial load will influence the dynamics behavior, especially stiffness information and vibration response of the whole ground test system. In this paper, a set of procedures are presented to remove the influence of air bearings and identify the true equivalent joint stiffness and damping from the test data of a motor-braked space manipulator with an air bearing support. First, inertia parameters are identified. Then, the equivalent joint stiffness and damping are determined by using a genetic algorithm (GA) method. Finally, true vibration characteristics of the manipulator are estimated by removing the additional inertia caused by the air bearings. Moreover, simulations and experiments are carried out to validate the presented procedures.
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http://dx.doi.org/10.3389/frobt.2021.641165 | DOI Listing |
J Org Chem
January 2025
Institute for Research in Biomedicine (IRB Barcelona). The Barcelona Institute of Science and Technology (BIST), Baldiri Reixach 10, 08028 Barcelona, Spain.
A novel chiral ligand, named MAdPHOS, bearing a P-stereogenic phosphane and a diadamantyl phosphane linked by a NH bridge has been synthesized. This bulky, C-symmetric, PNP ligand has been prepared from enantiopure -butylmethyl aminophosphane and was obtained as a crystalline solid. The NH/PH tautomerism, air-stability, and σ-donor capacity of MAdPHOS have been assessed herein.
View Article and Find Full Text PDFISA Trans
January 2025
State Key Laboratory of Tribology in Advanced Equipment, Department of Mechanical Engineering, Tsinghua University, Beijing, 100084, China; Beijing Key Laboratory of Transformative High-end Manufacturing Equipment and Technology, Tsinghua University, Beijing, 100084, China. Electronic address:
Multi-axis contouring control is crucial for ultraprecision manufacturing industries, contributing to meeting the ever-increasingly stringent performance requirements. In this article, a novel contouring adaptive real-time iterative compensation (CARIC) method is proposed to achieve extreme multi-axis contouring accuracy, remarkable trajectory generalization, disturbance rejection, and parametric adaptation simultaneously. Specifically, control actions generated by CARIC consist of robust feedback, adaptive feedforward, and online trajectory compensation components.
View Article and Find Full Text PDFJ Environ Manage
January 2025
Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, Niezapominajek 8, 30-239, Kraków, Poland.
To clean or not to clean? The solution to this dilemma is related to understanding the plasticiser migration which has a few practical implications for the state of museum artefacts made of plasticised poly(vinyl chloride) - PVC and objects stored in their vicinity. The consequences of this process encompass aesthetic changes due to the presence of exudates and dust deposition, an increase in air pollution and the development of mechanical stresses. Therefore, this paper discusses the plasticiser migration in PVC to provide evidence and support the development of recommendations and guidelines for conservators, collection managers and heritage scientists.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433, United States.
Biocement is an environmentally friendly alternative to traditional cement that is produced via microbially induced calcium carbonate precipitation (MICP) and has great potential to mitigate the environmental harms of cement and concrete use. Current production requires on-site bacterial cultivation and the application of live culture to target materials, lacking the convenience of stable formulas that enable broad adoption and application by nonscientific professionals. Here, we report the development of a dry shelf-stable formulation of , the model organism for biocement production.
View Article and Find Full Text PDFJ Orthop Surg Res
January 2025
Department of Orthopedic Surgery, Beijing Chaoyang Hospital, Capital Medical University of China, Gongti South Rd, No. 8, Beijing, 100020, China.
Objective: This study aims to investigate changes in matrix metalloproteinase (MMP) and tissue inhibitor of metalloproteinase (TIMP) levels in the intervertebral discs of New Zealand white rabbits under simulated overload and microgravity conditions, focusing on the expression of MMP1, MMP3, and TIMP1. The findings aim to provide a theoretical foundation for preventing and delaying lumbar disc degeneration in these environments.
Methods: Overload was simulated using an animal centrifuge, and microgravity was mimicked through tail suspension.
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