Due to the ability to improve the low-inertia characteristics of power systems and offer reliable voltage and frequency support, grid-forming permanent-magnet synchronous-generator wind turbines (PMSG-WTs) based on virtual synchronous-generator (VSG) technology are emerging se the direction for future developments. Previous studies on the small-signal stability of grid-forming PMSG-WTs that connect to the grid usually simplify them into grid-connected grid-side converters (GSC), potentially leading to errors in stability analyses. Therefore, this paper considers the machine-side converter (MSC) control and establishes impedance models for grid-forming PMSG-WTs. Based on the sensitivity calculation of controller parameters using symmetric difference computation based on zero-order optimization, the impact of the internal controller on outside impedance characteristics is quantitatively analyzed. Additionally, an optimization method to enhance the stability of a hybrid wind farm by adjusting the ratio of grid-forming and grid-following wind turbines is proposed.

The rapid development of spacecraft on-orbit services has increased the requirements for docking technology, especially for large-scale payloads that exceed the launch envelope. Docking technology based on astronaut extravehicular activities is one of the most promising directions for on-orbit services. In view of this, this paper designs and characterizes a handheld double-point docking mechanism for assembling large-scale payloads that is suitable for extravehicular activity (EVA) in dual-astronaut collaborative operations. It achieves the functional decoupling of docking, locking, unlocking, and separation throughout the whole process. The mechanism also has excellent design for human factors engineering, allowing astronauts to change hands, operate with one hand, and apply limited force. The mechanism adopts a dual-point probe–drogue configuration, while the misalignment tolerance design guarantees the docking accuracy and the operating range, and forms a rigid structural connection through a force amplification mechanism. Theoretical analysis and numerical simulations are implemented to estimate the dynamics, statics, and kinematics of the docking process. Corresponding experiments of the prototype are also conducted, including high–low temperature dynamics, docking tests, and kinematic tolerance experiments. The experiments validate the finite element analysis and verify the actual performance of the mechanism. The designed handheld dual-point docking mechanism was successfully applied for the first time by the Shenzhou 15 crew on China’s Space Station in March 2023. This paves a new road for spacecraft on-orbit service of large-scale payloads by EVAs, providing guidance as well as a technical foundation for the on-orbit construction of large spacecraft in the future.

During oil and gas exploration, the continuous growth of drilling operations imposes urgent requirements on the full life cycle management of drilling tools. To facilitate the direct identification of identity and characteristic data from embedded tags at the wellhead, especially for drilling tools undergoing composite motion at the wellhead, this paper investigates a stationary antenna system based on radio frequency identification (RFID) technology. To overcome challenges under harsh wellhead conditions, such as drilling fluid attenuation, tag polarization mismatch, frequency detuning, and identification blind zones caused by drilling tool movement, this paper establishes the design objectives for a high-gain, circularly polarized, and broadband antenna through electromagnetic field theory analysis. A dual-patch microstrip antenna array is designed accordingly. Simulations demonstrate the effects of critical parameters—such as patch spacing, truncation size, feed point position, and the annular slot—on the antenna’s impedance matching and circular polarization performance. A physical prototype of the antenna was fabricated, and microwave anechoic chamber tests were conducted; the measured results demonstrated strong consistency with the simulation design, achieving a gain of over 11dBi and an AR of less than 3 dB within the 880–950 MHz frequency bandwidth. Furthermore, based on the performance of the antenna unit, a 3D composite motion model of the drilling tool was established, to theoretically derive the strict boundary inequalities between antenna beamwidth, deployment distance, and moving speed. Based on these boundaries, a multi-antenna identification system with a spatiotemporal-synergistic polling strategy was constructed to eliminate dynamic identification blind zones and polarization mismatches with minimal hardware redundancy. Dynamic performance tests and parameter sensitivity analyses are conducted on an indoor rotary table. Conventional general-purpose RFID setups rely on static illumination or manual scanning, which completely fail under fluid-induced frequency detuning and high-speed composite motion. Unlike these setups, the fundamental distinction of the proposed system lies in an application-specific electromagnetic-kinematic mapping mechanism. This approach directly matches asymmetric beam profiling to the strict physical boundaries of wellhead constraints, guaranteeing deterministic identification with zero blind zones. This work lays a solid technical foundation for the wellhead data sensing link in the full life-cycle management of drilling tools, offering promising application prospects at the wellsite.