We present a dynamically reconfigurable spoof surface plasmon polariton (SSPP) waveguide capable of bidirectional switching between perfect absorption and perfect transmission through active control. Nonlinear varactor diodes are integrated into the waveguide, enabling degenerate phase matching between pump and signal waves via voltage-tuned dispersion engineering. Three-wave mixing processes are established, allowing bidirectional phase-controlled transitions from destructive to constructive interference. The proposed SSPP waveguide overcomes traditional pumping constraints with its bidirectional configuration, supporting both forward- and backward-propagating pump-signal configurations and permitting signal amplitude modulations at both the transmitter and receiver ends. Experimental characterization demonstrates remarkable signal gain tunability: the forward pumping configuration achieves a dynamic range spanning from −69.50 to +1.04 dB, while the backward configuration spans from −70.49 to +1.45 dB. This work provides new design paradigms for microwave coherent systems and advances the development of reconfigurable electromagnetic devices for adaptive energy harvesting and high-speed signal processing applications.

This paper reports a social media analysis study proposed by the Beijing Municipal Institute of Urban Planning and Design. The purpose is to explore techniques that can help the urban planning administrations to improve the social sensing and social perception abilities under the evolving data and technology environments. A framework integrating a comprehensive set of text mining algorithms is presented to conduct topic modeling, text clustering, event evolution detection, sentiment analysis, opinion mining, and information extraction on user-generated contents in Chinese social media. A domain ontology of Beijing urban planning is constructed to facilitate the text mining processes. Evaluations on two large, real-world datasets composed of microblogs and WeChat articles about the residential community and school education in Beijing demonstrate the effectiveness of our framework. The study illustrates the power of combining machine learning with knowledge-based, semantic approaches in analyzing social media for the domain of interest.