Article
Astronomy & Astrophysics
Yi-Han Wang, Rosalba Perna, Nathan W. C. Leigh, Michael M. Shara
Summary: Exoplanetary observations show that the occurrence of hot Jupiters is related to star clustering. Interactions between planetary systems and close flyby stars in star clusters can change the structure of primordially coplanar, circular planetary systems. This study focuses on the formation of hot Jupiters in multiplanet systems, using high-precision simulations. The results demonstrate that a single close flyby can activate secular chaos and lead to hot Jupiter formation through high-eccentricity migration. The formation rate of hot Jupiters is influenced by the size of the planetary system and the mass of the outer planet. Clusters with low density are more likely to have flyby-induced secular chaos, which contributes significantly to hot Jupiter formation.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Engineering, Mechanical
Aijun Hu, Suixian Liu, Ling Xiang, Yue Zhang
Summary: This paper proposes a dynamic model for multi-stage planetary gear system with crack fault and analyzes the dynamic responses of the system using various analysis methods. The results show that the crack fault has a significant impact on the system's dynamic characteristics and may lead to chaotic motion.
ENGINEERING FAILURE ANALYSIS
(2022)
Article
Green & Sustainable Science & Technology
Qi Liu, Jing Yang, Lei Gao, Yucheng Dong, Zhaoxia Guo, Enayat A. Moallemi, Sibel Eker, Michael Obersteiner
Summary: This study conducted robust sensitivity analyses of scenario parameters in a complex socio-ecological system model and identified sensitive parameters that remain sensitive under five representative scenarios. The findings make it easier to improve and apply the model by focusing on key parameters and understanding important sector linkages in socio-ecological systems.
JOURNAL OF CLEANER PRODUCTION
(2023)
Article
Mathematics, Interdisciplinary Applications
Suixian Liu, Aijun Hu, Yuyan Sun, Ling Xiang, Yancheng Zhu
Summary: A dynamic modeling method for Multistage Planetary Gear Transmission (MPGT) is proposed, taking into account the integrated interaction of multiple nonlinear parameters. The time-varying mesh stiffness of each gear pair is calculated by the energy method. The effects of input torque, gear backlash, and meshing damping on the chaos and impact characteristics of the system are analyzed in detail. The results show that increasing the input torque and meshing damping can suppress the chaotic motion and enhance the stability of the system, while a slightly larger backlash is necessary to improve the vibration characteristics of the system. These findings can guide the design of dynamic characteristics and vibration control of the MPGT.
INTERNATIONAL JOURNAL OF BIFURCATION AND CHAOS
(2023)
Review
Astronomy & Astrophysics
Joseph G. O'Rourke, Colin F. Wilson, Madison E. Borrelli, Paul K. Byrne, Caroline Dumoulin, Richard Ghail, Anna J. P. Gulcher, Seth A. Jacobson, Oleg Korablev, Tilman Spohn, M. J. Way, Matt Weller, Frances Westall
Summary: Venus, once thought to be a verdant world, was later discovered to have a hellish surface. The evolution of Venus and its potential similarities to other planets, including exoplanets, are of great scientific interest.
SPACE SCIENCE REVIEWS
(2023)
Article
Environmental Sciences
Nancy J. Chanover, James M. Bauer, John J. Blalock, Mitchell K. Gordon, Lyle F. Huber, Mia J. T. Mace, Lynn D. V. Neakrase, Matthew S. Tiscareno, Raymond J. Walker
Summary: While fewer missions have been conducted to the outer Solar System compared to the inner Solar System, these missions to the giant planets have provided valuable data that continue to shape our understanding of these complex systems. The data are stored in national and international planetary archives and can be accessed through the NASA Planetary Data System (PDS). The PDS will serve as the main repository for future missions' data and support research on the interpretation of the existing data.
Article
Astronomy & Astrophysics
Sheng Yang, Liangyu Wu, Zekai Zheng, Masahiro Ogihara, Kangrou Guo, Wenzhan Ouyang, Yaxing He
Summary: Studying the orbital stability of multi-planet systems is crucial for understanding planet formation, estimating stable time, and advancing population synthesis models. This study investigates the dynamical stability of non-uniform separation systems. A system with 10 planets and varying orbital separations was simulated, showing that reducing one pair of spacing led to significantly shorter orbital crossing times. The first collisions were closely associated with the initially closest separation pair. Updating formulas derived for evenly spaced systems is necessary in realistic situations.
Article
Engineering, Electrical & Electronic
Pengfei Yan, Yaning Li, Qiang Gao, Tao Wang, Chen Zhang
Summary: This research investigates the coupled phase-tuning mechanism of two-stage planetary gear systems and its relationship with the coupled vibration of the system. It derives the phase-coupled tuning mechanism of the two-stage planetary system based on meshing force relationships and coupling characteristics between different stages. The excitation and suppression relationships associated with the teeth number, harmonic order, and coupling vibration of the coupled system are clearly described. A nonlinear dynamic model is used to study the effect of coupled phase tuning on the vibration response of a two-stage planetary gear system. The correctness of the phase-coupling tuning law is further verified through experimental analysis.
Article
Astronomy & Astrophysics
N. Borisov, H. Krueger
Summary: Research suggests that Jupiter's inner magnetosphere is warm and dense, contradicting the shadow resonance mechanism proposed by some scientists. Instead, it is argued that dust grains in the Thebe extension mainly come from larger grains ejected from Thebe due to micrometeoroid bombardment. Large dust grains in the Thebe extension oscillate, while smaller grains ejected from Thebe migrate quickly into the Thebe ring.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2021)
Article
Multidisciplinary Sciences
Miles Cranmer, Daniel Tamayo, Hanno Rein, Peter Battaglia, Samuel Hadden, Philip J. Armitage, Shirley Ho, David N. Spergel
Summary: The study introduces a Bayesian neural network model that accurately predicts the stability of planetary systems, with training code available and significantly faster and more accurate than existing methods.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Article
Engineering, Mechanical
Congfang Hu, Gaode Geng, Pol D. Spanos
Summary: The closed differential planetary transmission system features a high-speed ratio and compact structure, but suffers from uneven load sharing and excessive errors. This study investigates the impact of error randomness on load-sharing behavior through establishing a stochastic multi-body dynamics model and comparing different methods.
MECHANISM AND MACHINE THEORY
(2021)
Article
Engineering, Aerospace
Andrea D'Ambrosio, Dario Spiller, Fabio Curti
Summary: This paper presents an improved metaheuristic algorithm for calculating suboptimal maneuvers in satellite formation flying, demonstrating its efficiency and reliability in solving space engineering problems.
ADVANCES IN SPACE RESEARCH
(2021)
Article
Meteorology & Atmospheric Sciences
Haruka Okui, Kaoru Sato, Dai Koshin, Shingo Watanabe
Summary: Research has shown that an elevated stratopause is formed following stratospheric sudden warming events, with atmospheric waves playing a key role in the mechanism, particularly through adiabatic heating from residual circulation and the generation of planetary waves.
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
(2021)
Review
Engineering, Electrical & Electronic
Bingwei Gao, Yongkang Wang, Guangbin Yu
Summary: This study summarizes the commonly used lumped-parameter, finite element, and rigid-flexible coupling models in studying the dynamic characteristics of traditional planetary gear systems. It also summarizes the research status of gear-rotor and planetary gear systems in both inertial and non-inertial systems, and the progress in load characteristics, vibration characteristics, and vibration control of traditional planetary gear systems. Finally, the study suggests some future development directions.
Article
Engineering, Mechanical
Xinbin Li, Jing Liu, Jin Xu, Yan Chen, Zeng Hu, Guang Pan
Summary: This study proposes a time-varying wear model for planetary bearings in a double planetary gear set, which helps to analyze the performance degradation of the gear set. The dynamic model incorporates the time-varying behavior of sliding speeds and contact forces, as well as bearing and gear excitations. The results show that the wear of the inner ring of the planetary bearing is more severe than the outer ring, and it affects the dynamics of rollers, carriers, planet gears, and cages.
NONLINEAR DYNAMICS
(2023)