Chengdu Guoke Haibo Information Technology (China)

Abstract In this paper, a wideband directional coupler is proposed for high‐power applications, which is composed of a transformer and lumped elements. The introduction of the transformer greatly improves the directivity of the coupler. The measurement results demonstrate that the proposed design has an excellent return loss (>17 dB), small insertion loss (<0.4 dB), and high directivity (>22) over a wide frequency band (10–350 MHz). Meanwhile, it can achieve a flat coupling level of 32 dB with the imbalance less than 0.5 dB.

Based on the characteristics of the new power system with many points, wide range and unattended, this paper studies the specific Cyberspace security risks faced by the disease control side, the station side and the site side, and proposes a new power system Cyberspace security assurance system of “integration of collection, network, side, end, industry and people”. The site side security access measures, the site side civil air defense technology integration measures, the whole business endogenous security mechanism, the whole domain communication security mechanism, the integrated monitoring and early warning and emergency response mechanism are specifically adopted to form a comprehensive integrated security mechanism for the new power system, form a sustainable protection model, effectively improve the security capability, while taking into account the cost and operational complexity of specific implementation links, Provide comprehensive guarantee capability for the safe operation of the new power system.

Cybertwin-driven-based network architecture for sixth generation (6G) is a new cloud-centric network architecture, which was put forward to address challenges of 6G, such as scalability, security, mobility, and availability. As more and more users’ data are obtained and converted into other digital asset by the cybertwin, relevant techniques of data management to enhance privacy and security becomes a key challenge for Cybertwin-driven 6G. The double authentication preventing ring signature (DAPRS) is a cryptographic primitive that meets requirements of authenticity, anonymity of users’ private data, and linkability of users’ misbehavior, so it is suitable for monitoring behaviors of risky users. In this article, we propose a post-quantum secure ring signature to enhance security and privacy in Cybertwin-driven 6G (PRSG). In the PRSG, we first put forward an accumulator based on a chameleon hash function that allows to efficiently prove knowledge of an accumulated value. Then, we construct a DAPRS based on the accumulator and the zero-knowledge argument of knowledge. Finally, we present how to use the DAPRS to build a secure and efficient privacy-preserving scheme in the Cybertwin-driven 6G. Security proof shows that this scheme achieves anonymity, unforgeability, as well as double signature extractability. Also, we make some security analysis and performance evaluation to demonstrate that the PRSG has low communication complexity, high performance, and privacy preservation in the cybertwin-driven 6G.

Theoretical analyses of the dynamic properties of a 2-2 multi-layered cement-based piezoelectric composite are presented based on the theory of piezoelasticity and D’Alembert’s principle. An arbitrary mechanical load acts on the free end of the composite in the form of pressure. The Taylor series expansion method is introduced for the arbitrary mechanical load, and the theoretical solutions of the composite are obtained mainly based on the eigenfunction expansion method, Duhamel integral, and Laplace transform. Comparisons between the theoretical results, numerical results, and four related theoretical studies are presented, and good agreements are found. Furthermore, the theoretical expression of magnification factors of the composite under the harmonic load are obtained and analyzed. In addition to providing a theoretical basis for the design and experimentation of 2-2 cement-based piezoelectric composites under the arbitrary loading, the theoretical methods presented in the article could be extended to analyze the dynamic characteristics of any multilayered composite structure.

Abstract Silicon‐based material as lithium‐ion anodes has attracted huge attention owing to their ultrahigh capacity. However, they usually undergo severe volume expansion over the repeated lithiation/delithiation processes and have low electronic conductivity, leading to the inferior cycling stability and the poor rate capability. Here, an in‐situ growth of carbon nanotubes (CNTs) on the surface of SiO composite was prepared and then encapsulated by the amorphous carbon derived from high softening point pitch. SEM and TEM studies show that SiO was firmly wrapped with CNTs and well coated with the amorphous carbon. Meanwhile, nitrogen adsorption‐desorption measurement indicated the prepared composite SiO@CNTs/C was hierarchical pore structure, which can shorten the lithium‐ion transport pathway and enhance the structural stability. The prepared SiO@CNTs/C exhibited an excellent long‐term cycling stability (a high reversible specific capacity of 821.7 mAh g −1 , and a high capacity retention of 95.9% to the 3rd cycle after 200 cycles), and prominent rate capacity, indicating the great potential of SiO@CNTs/C anode for practical application.

Montgomery modular multiplication (MMM) plays a crucial role in the implementation of modular exponentiations of public‐key cryptography. In this paper, we discuss the iterative structure and extend the iterative bound condition of MMM. It can be applied to complicated modular exponentiations. Based on the iterative condition of MMM, we can directly use non‐modular additions, subtractions and even simple multiplications instead of the modular forms, which make modular exponentiation operation very efficient but more importantly iterative applicability of MMM.