Browsing by Author "Ma, Jie"

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    Development of a Physical Substructure for Real-Time Hybrid Simulation of an Active Thermal Control System
    (2024 International Conference on Environmnetal Systems, 2024-07-21) Rhee, Seungho; Park, Hyunjin; Ma, Jie; Silva, Christian E.; Lee, Sangwook; Ziviani, Davide
    In space, thermal management systems operate under conditions that differ significantly from those on Earth. These systems are exposed to intense solar radiation and extreme fluctuations in surface temperature. Moreover, they cannot dissipate heat through conduction and convection, but instead through conduction and radiation from the refrigerant to the space because of the near-vacuum condition. Consequently, typical experimental methods employed in laboratory environments are limited in their ability to capture the realistic, complex dynamics, and unpredictable behaviors of the system in space conditions. To address these limitations, this paper proposes a Real-Time Hybrid (RTH) testing framework of an Active Thermal Control System (ATCS) designed for deep space habitats, with an emphasis on lunar habitats. The RTH framework integrates both physical and cyber subsystems through transfer systems, allowing for comprehensive testing under desired space conditions and scenarios. In this paper, the physical subsystem of an ATCS built in a laboratory environment is introduced. Furthermore, three types of characterization tests are conducted to demonstrate the dynamic behaviors and capabilities of the physical substructure, which will enable the development of the entire RTH simulation of an ATCS.
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    On stability of linear switching systems
    (2016-05) Ma, Jie; Wang, Alex; Ghosh, Bijoy K.; Ibragimov, Akif; Ren, Beibei
    This dissertation is about switching systems. In chapter 1, the background of stability of linear switching systems is introduced; In chapter 2, some su cient conditions in terms of relation between eigenvalues and eigenvectors of switching matrices are given for asymptotic stability under arbitrary switching scheme, and are followed by several examples for n = 2; In chapter 3, some results about stability after state feedback are discussed, and a necessary and su cient condition is given for the existence of a common quadratic Lyapunov function of the closed-loop system; In chapter 4, it is shown that asymptotic stability depends on the average switching rate; some methods to obtain maximal switching rate are given, especially when switching matrices are semi-simple.