为了支持网络环境下的复杂公共问题决策,探讨了BBS系统对于公共问题决策的支持潜力及其不足,提出了公共论坛系统PFS(Public Forum System)的设计构成。这个系统包括公共问题决策过程中帮助公众实现从信息层面到智慧层面的认知进化的两...为了支持网络环境下的复杂公共问题决策,探讨了BBS系统对于公共问题决策的支持潜力及其不足,提出了公共论坛系统PFS(Public Forum System)的设计构成。这个系统包括公共问题决策过程中帮助公众实现从信息层面到智慧层面的认知进化的两种系统转换,为未来公共问题决策的决策民主性与有效性结合提出了新的模式。展开更多
Vibration energy harvesters(VEHs) can transform ambient vibration energy to electricity and have been widely investigated as promising self-powered devices for wireless sensor networks, wearable sensors, and applicati...Vibration energy harvesters(VEHs) can transform ambient vibration energy to electricity and have been widely investigated as promising self-powered devices for wireless sensor networks, wearable sensors, and applications of a micro-electro-mechanical system(MEMS). However, the ambient vibration is always too weak to hinder the high energy conversion efficiency. In this paper, the integrated frame composed of piezoelectric beams and mechanical amplifiers is proposed to improve the energy conversion efficiency of a VEH. First, the initial structures of a piezoelectric frame(PF) and an amplification frame(AF) are designed. The dynamic model is then established to analyze the influence of key structural parameters on the mechanical amplification factor. Finite element simulation is conducted to study the energy harvesting performance, where the stiffness characteristics and power output in the cases of series and parallel load resistance are discussed in detail. Furthermore, piezoelectric beams with variable cross-sections are introduced to optimize and improve the energy harvesting efficiency. Advantages of the PF with the AF are illustrated by comparison with conventional piezoelectric cantilever beams. The results show that the proposed integrated VEH has a good mechanical amplification capability and is more suitable for low-frequency vibration conditions.展开更多
文摘为了支持网络环境下的复杂公共问题决策,探讨了BBS系统对于公共问题决策的支持潜力及其不足,提出了公共论坛系统PFS(Public Forum System)的设计构成。这个系统包括公共问题决策过程中帮助公众实现从信息层面到智慧层面的认知进化的两种系统转换,为未来公共问题决策的决策民主性与有效性结合提出了新的模式。
基金Project supported by the National Natural Science Foundation of China (Nos. 11972051 and11672008)the Opening Project Foundation of the State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures (No. KF-2020-11)。
文摘Vibration energy harvesters(VEHs) can transform ambient vibration energy to electricity and have been widely investigated as promising self-powered devices for wireless sensor networks, wearable sensors, and applications of a micro-electro-mechanical system(MEMS). However, the ambient vibration is always too weak to hinder the high energy conversion efficiency. In this paper, the integrated frame composed of piezoelectric beams and mechanical amplifiers is proposed to improve the energy conversion efficiency of a VEH. First, the initial structures of a piezoelectric frame(PF) and an amplification frame(AF) are designed. The dynamic model is then established to analyze the influence of key structural parameters on the mechanical amplification factor. Finite element simulation is conducted to study the energy harvesting performance, where the stiffness characteristics and power output in the cases of series and parallel load resistance are discussed in detail. Furthermore, piezoelectric beams with variable cross-sections are introduced to optimize and improve the energy harvesting efficiency. Advantages of the PF with the AF are illustrated by comparison with conventional piezoelectric cantilever beams. The results show that the proposed integrated VEH has a good mechanical amplification capability and is more suitable for low-frequency vibration conditions.
