China Aerospace Science and Technology Corporation

Based on research into the applications of artificial intelligence (AI) technology in the manufacturing industry in recent years, we analyze the rapid development of core technologies in the new era of ‘Internet plus AI’, which is triggering a great change in the models, means, and ecosystems of the manufacturing industry, as well as in the development of AI. We then propose new models, means, and forms of intelligent manufacturing, intelligent manufacturing system architecture, and intelligent manufacturing technology system, based on the integration of AI technology with information communications, manufacturing, and related product technology. Moreover, from the perspectives of intelligent manufacturing application technology, industry, and application demonstration, the current development in intelligent manufacturing is discussed. Finally, suggestions for the application of AI in intelligent manufacturing in China are presented.

Rapid evolution of miniaturized, automatic, robotized, function-centered devices has redefined space technology, bringing closer the realization of most ambitious interplanetary missions and intense near-Earth space exploration. Small unmanned satellites and probes are now being launched in hundreds at a time, resurrecting a dream of satellite constellations, i.e., wide, all-covering networks of small satellites capable of forming universal multifunctional, intelligent platforms for global communication, navigation, ubiquitous data mining, Earth observation, and many other functions, which was once doomed by the extraordinary cost of such systems. The ingression of novel nanostructured materials provided a solid base that enabled the advancement of these affordable systems in aspects of power, instrumentation, and communication. However, absence of efficient and reliable thrust systems with the capacity to support precise maneuvering of small satellites and CubeSats over long periods of deployment remains a real stumbling block both for the deployment of large satellite systems and for further exploration of deep space using a new generation of spacecraft. The last few years have seen tremendous global efforts to develop various miniaturized space thrusters, with great success stories. Yet, there are critical challenges that still face the space technology. These have been outlined at an inaugural International Workshop on Micropropulsion and Cubesats, MPCS-2017, a joint effort between Plasma Sources and Application Centre/Space Propulsion Centre (Singapore) and the Micropropulsion and Nanotechnology Lab, the G. Washington University (USA) devoted to miniaturized space propulsion systems, and hosted by CNR-Nanotec—P.Las.M.I. lab in Bari, Italy. This focused review aims to highlight the most promising developments reported at MPCS-2017 by leading world-reputed experts in miniaturized space propulsion systems. Recent advances in several major types of small thrusters including Hall thrusters, ion engines, helicon, and vacuum arc devices are presented, and trends and perspectives are outlined.

Extracting roads from satellite imagery is a promising approach to update the dynamic changes of road networks efficiently and timely. However, it is challenging due to the occlusions caused by other objects and the complex traffic environment, the pixel-based methods often generate fragmented roads and fail to predict topological correctness. In this paper, motivated by the road shapes and connections in the graph network, we propose a connectivity attention network (CoANet) to jointly learn the segmentation and pair-wise dependencies. Since the strip convolution is more aligned with the shape of roads, which are long-span, narrow, and distributed continuously. We develop a strip convolution module (SCM) that leverages four strip convolutions to capture long-range context information from different directions and avoid interference from irrelevant regions. Besides, considering the occlusions in road regions caused by buildings and trees, a connectivity attention module (CoA) is proposed to explore the relationship between neighboring pixels. The CoA module incorporates the graphical information and enables the connectivity of roads are better preserved. Extensive experiments on the popular benchmarks (SpaceNet and DeepGlobe datasets) demonstrate that our proposed CoANet establishes new state-of-the-art results. The source code will be made publicly available at: https://mmcheng.net/coanet/.

SiC nanowires with a higher carbon unoccupied DOS possess more stacking faults, resulting in extensive energy dissipation under electromagnetic radiation.

Abstract Quaking (QKI) is an alternative splicing factor that can regulate circRNA formation in the progression of epithelial–mesenchymal transition, but the mechanism remains unclear. High expression of QKI is correlated with short survival time, metastasis, and high clinical stage and pathology grade in hepatocellular carcinoma (HCC). Here we report that transcription of the QKI gene was activated by the Yin-Yang 1 (YY1)/p65/p300 complex, in which YY1 bound to the super-enhancer and promoter of QKI, p65 combined with the promoter, and p300 served as a mediator to maintain the stability of the complex. This YY1/p65/p300 complex increased QKI expression to promote the malignancy of HCC as well as an increased circRNA formation in vitro and in vivo. Hyperoside is one of several plant-derived flavonol glycoside compounds. Through virtual screening and antitumor activity analysis, we found that hyperoside inhibited QKI expression by targeting the YY1/p65/p300 complex. Overall, our study suggests that the regulatory mechanism of QKI depends on the YY1/p65/p300 complex and that it may serve as a potential target for treatment of HCC. Significance: These findings identify the YY1/p65/p300 complex as a regulator of QKI expression, identifying several potential therapeutic targets for the treatment of HCC.

Covalently bonded SiC/Co hybrid nanowires have been fabricated. They present significantly increased electromagnetic absorption due to a synergistic coupling interaction.

Abstract Interannual variability of the terrestrial ecosystem carbon sink is substantially regulated by various environmental variables and highly dominates the interannual variation of atmospheric carbon dioxide (CO2) concentrations. Thus, it is necessary to determine dominating factors affecting the interannual variability of the carbon sink to improve our capability of predicting future terrestrial carbon sinks. Using global datasets derived from machine-learning methods and process-based ecosystem models, this study reveals that the interannual variability of the atmospheric vapor pressure deficit (VPD) was significantly negatively correlated with net ecosystem production (NEP) and substantially impacted the interannual variability of the atmospheric CO2 growth rate (CGR). Further analyses found widespread constraints of VPD interannual variability on terrestrial gross primary production (GPP), causing VPD to impact NEP and CGR. Partial correlation analysis confirms the persistent and widespread impacts of VPD on terrestrial carbon sinks compared to other environmental variables. Current Earth system models underestimate the interannual variability in VPD and its impacts on GPP and NEP. Our results highlight the importance of VPD for terrestrial carbon sinks in assessing ecosystems’ responses to future climate conditions.

The interest in steam reforming process as an efficient method for hydrogen production has been greatly increasing, due to its efficiency during hydrogen production and low environmental problems compared to other techniques. The main objective of this review was to present a comprehensive study of environmental, economic aspects of hydrogen production from steam reforming of raw materials such as biomass, bio-gas, ethanol, and natural gas. From literature review, it was found that among methods for hydrogen production, steam reforming of natural gas has lower installed capital due to the precence of high amounts of unconverted hydrocarbons in the produced gas (so-called tar) during other methods such as steam reforming of bio-gas.

Gallium oxide (Ga2O3), a typical ultra wide bandgap semiconductor, with a bandgap of ∼ 4.9 eV, critical breakdown field of 8 MV/cm, and Baliga's figure of merit of 3444, is promising to be used in high-power and high-voltage devices. Recently, a keen interest in employing Ga2O3 in power devices has been aroused. Many researches have verified that Ga2O3 is an ideal candidate for fabricating power devices. In this review, we summarized the recent progress of field-effect transistors (FETs) and Schottky barrier diodes (SBDs) based on Ga2O3, which may provide a guideline for Ga2O3 to be preferably used in power devices fabrication.

As the cornerstone mission of the fourth phase of the Chinese Lunar Exploration Program, Chang'E-7 (CE-7) was officially approved, and implementation started in 2022, including a main probe and a communication relay satellite. The main probe, consisting of an orbiter, a lander, a rover and a mini-flying probe, is scheduled to be launched in 2026. The lander will land on Shackleton crater's illuminated rim near the lunar south pole, along with the rover and mini-flying probe. The relay satellite (named Queqiao-2) will be launched in February 2024 as an independent mission to support relay communication during scientific exploration undertaken by Chang'E-4, the upcoming Chang'E-6 in 2024 and subsequent lunar missions. The CE-7 mission is mainly aimed at scientific and resource exploration of the lunar south pole. We present CE-7's scientific objectives, the scientific payloads configuration and the main functions for each scientific payload with its key technical specifications.

This paper investigates the adaptive tracking-control problem for a class of nonlinear systems with uncertain parameters, disturbance, and unmodeled dynamics. A novel model reference adaptive control (MRAC) with external filter is proposed to not only stabilize the error system but also guarantee its transient performance. The proposed control strategy can mathematically ensure designable L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> norm bounds of the difference between the original model's and the reference model's state and their control inputs as well. On the other hand, the reference model, which is deemed as a linear time-invariant (LTI) system, can be designed to run in a desired performance level by selecting a suitable filter in the control structure. Another improvement emphasizes that the proposed approach can attain the above performance without using a high-static adaptation gain, which avoids the possible negative effects in the context of robustness. Finally, simulation on a high-accuracy motion-system model driven by a direct-current (dc) motor is given to verify the proposed approach, and the effectiveness is shown based on the simulation curves and analysis.

Abstract China’s first Mars exploration mission (HuoXing-1) has been named as ‘Tianwen-1’ meaning Heaven Inquiry. Tianwen-1 was launched on July 23, 2020. In this paper, the scientific objectives of earlier and current Mars exploration missions worldwide are reviewed, and the scientific objectives, payloads and preliminary scientific investigation plan of China’s first Mars exploration mission are introduced, and expected scientific achievements are analyzed.

Abstract Hydrogel electronics have attracted growing interest for emerging applications in personal healthcare management, human‐machine interaction, etc. Herein, a “doping then gelling” strategy to synthesize supramolecular PANI/PAA hydrogel with a specific strand entangled network is proposed, by doping the PANI with acrylic acid (AA) monomers to avoid PANI aggregation. The high‐density electrostatic interaction between PAA and PANI chains serves as a dynamic bond to initiate the strand entanglement, enabling PAA/PANI hydrogel with ultra‐stretchability (2830%), high breaking strength (120 kPa), and rapid self‐healing properties. Moreover, the PAA/PANI hydrogel‐based sensor with a high strain sensitivity (gauge factor = 12.63), a rapid responding time (222 ms), and a robust conductivity‐based sensing behavior under cyclic stretching is developed. A set of strain sensing applications to precisely monitor human movements is also demonstrated, indicating a promising application prospect as wearable devices.

In this paper, an adaptive fast terminal sliding mode control control law (AFTSMCL) is presented to resolve attitude tracking control problem for rigid spacecraft, which can provide finite-time convergence, strong robustness, and fault-tolerant control. Rigorous proof is achieved first. Simulation results are presented to illustrate the effectiveness of presented control law.

Since 1980, defined benefit plans have steadily lost market share to defined contribution plans. In 1979, defined contribution plans had 17 percent of the primary pension market. By 1988, it was 34 percent. About half of the shift is attributable to a loss of employment in large unionized firms where defined benefit plans are used intensively. But evidence of large changes in preferences is also found in the data. One likely explanation is the introduction of a new variety of defined contribution plans, so‐called 401(k)s. These pension plans have productivity traits that make them more effective competition for defined benefit plans.

The association between marital status and health among men has been well documented, but few studies track health trajectories following family structure transitions among unmarried fathers. Using the Fragile Families and Child Wellbeing Study this article examines trajectories of paternal mental health and self-rated health, focusing on transitions into and out of residential relationships with the child's biological mother or a new partner during a five-year post-birth period (N = 4,331). Continuously married fathers report higher time-specific self-rated health and fewer mental health problems than continuously single fathers, controlling for underlying health trajectories. The disparity, however does not increase over time, providing little support for the marital resource model during these years. Static group differences suggest that resources fathers carry with them into unions may buffer them from the negative effects of union dissolution. The implications of these findings for cohabitation, as well as selection and causation arguments, are also discussed.

This paper presents a compact-size, low-cost smart antenna with electronically switchable radiation patterns, and reconfigurable polarizations. This antenna can be dynamically switched to realize three different polarizations including two orthogonal linear polarizations and one diagonally linear polarization. By closely placing several electronically reconfigurable parasitic elements around the driven antenna, the beam switching can be achieved in any of the three polarization states. In this design, a polarization reconfigurable square patch antenna with a simple feeding network is used as the driven element. The parasitic element is composed of a printed dipole with a PIN diode. Using different combinations of PIN diode <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on/off</small> states, the radiation pattern can be switched toward different directions to cover an angle range of 0° to 360° in the azimuth plane. The concept is confirmed by a series of measurements. This smart antenna has the advantages of compact size, low cost, low power consumption, reconfigurable polarizations, and beams.

Abstract In attempting to understand the course of human evolution and the nature of hominid adaptation over the past few million years, it is necessary to consider prevailing evidence from all parts of the world. Eastern Asia provides a range of important questions and challenges with regard to this evolutionary puzzle. Although evidence for earlier ape evolution is present in China (for example, at Lufeng in Yunnan Province), the earliest evidence for hominid presence appears to be in the Early Pleistocene, apparently the result of a migration of hominids to and subsequent adaptation within Eastern Asia. The archeological record provides a closer look at some technological aspects of this adaptation during the Early and Middle Pleistocene, showing both distinctive contrasts and intriguing continuities relative to the rest of the Old World.

This paper deals with the second-order dynamic sliding-mode control (SODSMC) problem for nonminimum phase underactuated hypersonic vehicles. First, the underactuated hypersonic vehicle attitude control model is introduced. The normal form and the nonminimum phase nature for the vehicle are discussed. Thus, the nonminimum phase system is divided into the minimum phase subsystem and the nonminimum phase subsystem via the system decomposition approach. Second, the SODSMC scheme is developed. The conventional sliding-mode controller and the second-order dynamic sliding-mode controller are designed for the two subsystems. Besides, the dynamic sliding manifold is provided for the nonminimum phase subsystem. Simulation results for the nonminimum phase underactuated hypersonic vehicle are presented to demonstrate the effectiveness and robustness of the proposed control scheme.

The thermal conductivities of vinyl endblocked polymethylsiloxane reinforced with silicone nitride (Si 3 N 4 ) particles alone or in combination with silicone carbide whisker (SiC w ) were investigated in this article. The results indicate that the silicone rubber incorporating of 50 vol% hybrid Si 3 N 4 particles of different sizes at an optimal weight ratio exhibited the highest thermal conductivity of 1.48 W/m K compared to each single particle size filler used only; moreover, the combined use of hybrid Si 3 N 4 and SiC w with the weight ratio of 9:1 provided the composites with higher thermal conductivity due to the structuring filler in hybrid fillers, improved thermal stability and reduced coefficient of thermal expansion (CTE) for comparison with the hybrid Si 3 N 4 particles used alone. In addition, the surface treatment of the hybrid fillers with 3-methacryloyloxy-propyltrimethoxysilane enhanced the thermal conductivity and reduced CTE of the composites.