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The low-frequency disturbances transmitted by flexible cables are difficult to be attenuated for a novel disturbance-free payload spacecraft, which decreases the payload’s pointing accuracy and stability. In this research, a new spacecraft configuration with a high-precision inertial reference unit composed of capacitive sensors and a spherical test mass is proposed. The disturbance attenuation and pointing control system is subdivided into four interconnected control loops. The payload can be isolated from disturbances in the all-frequency band by the active vibration isolation control loop and the drag-free control loops, and its high-precision pointing requirement can be satisfied with the attitude pointing control loop and the attitude tracking control loop. An integrated control strategy is proposed, and the control system is decoupled into 12 single-input single-output control loops by pre-compensating, which lays the foundation for feedback design. Through the amplitude-frequency response analysis, the control bandwidth is designed according to the Proportional-Integral-Differentive control algorithm. The numerical simulations show that the disturbance attenuation performance is better than −20 dB in the all-frequency band, and the pointing accuracy and the pointing stability are better than 10−6 deg and 10−7 deg/s, respectively. The new spacecraft configuration and the disturbance attenuation and pointing control system provide a general technical solution for payloads with high-precision and high-stability requirements.

Formal concept analysis can use concept lattice and (attribute) implication to visualize and represent knowledge. Decision implication is a special implication, and the study of decision implication is to establish and study one or more closed subsystems in implications, including decision implication subsystem and corresponding semantic and syntactic subsystems. In order to further clarify the relationship between implications and decision implications, it is studied whether the implication systems can be obtained from these decision implications subsystems. In fact, if implications can be deduced from decision implications, the studies on implications and canonical basis can be reduced to the studies of decision implications and decision implication canonical basis. Firstly, some sufficient and necessary conditions are given to determine whether implications can be represented by decision implication. Secondly, an example is given to show that there are some implications that cannot be represented by decision implications, and thus the representation of implications is further divided into direct and indirect representations. Finally, by studying the characteristics of the implication that cannot be directly represented when there is only one decision attribute in decision contexts, a sufficient and necessary condition is presented to determine whether implications cannot be directly represented by decision implication, and a generation method is also designed to generate the implications that cannot be directly represented. This study provides a new perspective for the study of implications and canonical basis, and also forms a foundation for further theoretical study on formal concept analysis.

The characteristics of polyimide film hypervelocity impacted (HVI) by micro flyer are investigated though experimental and numerical methods. Using the laser driven flyer (LDF) method combined with the technique of scanning electron microscopy (SEM) and explicit dynamics numerical algorithm, the fracture morphology and detailed mechanical responses of polyimide film, both in the impact and non–impact zones, are captured; and a dynamic fracture strain criteria, combing temperature and strain rate, is presented. A parametric study on the performance of polyimide film is implemented and the influence of the factors, including the impact velocity, film thickness, strain rate constant and pre–stress, are assessed. The research reveals that polyimide film exits two failure modes, i.e. ductile punching and brittle cracks. Polyimide materials in the impact zone have experienced a high temperature (>Tg = 685 K), ultrahigh strain rate (108∼109) and plastic state; while in the non–impact zone, it is normal temperature (293–295 K), high strain rate (105∼106) and elastic state.

This paper reports the ignition performance of the iodine-fueled radio frequency (RF) ion thruster (IRIT) at different anode temperatures ( T a0 ). The experimental results show that the anode temperature plays important role on the ignition process of the IRIT. There were two characteristic temperatures related to the anode: the minimum ignition temperature ( T i0 ) and the stable ignition temperature ( T is ), which were much lower than the pipeline temperature and the storage tank temperature. At T a0 T i0 , it failed to discharge. When T i0 ≤ T a0 < T is , it was ignited with dramatical oscillations. At T a0 ≥ T is , the discharge was stable in a large anode temperature range. The analysis showed that the different discharge phenomena at different anode temperatures were attributed to the change of iodine flow rate during the process of the iodine deposition-clogging and sublimation-clearing inside the thruster. The research helps improve the preheating design of the iodine-fueled electric thruster.

Polypropylene (PP) films were grafted respectively with two different processes: air plasma graft (APG) and post-plasma grafting (PPG) using feather keratin. The graft results were compared by measuring contact angles, printability, ageing test and surface chemical composition analysis. The results showed that the surface hydrophilic and printing properties of the PP films after PPG were better than after APG. The contact angles went down from 34.7° to less than 10° and could sustain to 28° at the end of the test (30 days). The analyses of the C1s and N1s peaks by X-ray photoelectron spectroscopy (XPS) illustrated that polar groups, especially nitrogen-containing groups C–NHx and CO–NH, were introduced on the PP surface after PPG. The mechanisms of PPG were briefly discussed.

Summary form only given. A novel radio frequency (rf) dielectric barrier glow discharge plasma (DBGD) was utilized to evaluate the AZ9912 photoresist (PR) stripping effect. Argon (Ar) and oxygen (O2) were employed as working gases and ignited under atmospheric pressure. The discharge power efficiency was calculated based on the Lissajous plot and could reach to 80%. Compared to rf atmospheric glow discharges generated with bare electrodes, the DBGD remains stable and uniform over a larger current. Time dependant dielectric breakdown (TDDB) testing was conducted to evaluate the reliability of gate oxide on MOS capacitors. The surface of the etched PR was characterized using optical microscope and atomic force microscope (AFM). The results showed that there were no visible residues and plasma-induced ion bombardment damage left on the surface. Optical Emission Spectroscopy (OES) was also used to study the working species during the stripping process and the results showed that the possible useful active species belong to the atomic O and OH radical.