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346 results on '"Dai, Keren"'

111. Design and Experiment of Shielding Package for Electronic Devices in Pulsed Strong Magnetic Field

Author

Liu Peng, Yang Yuxin, Zhang He, Yin Qiang, and Dai Keren

Subjects
Railgun, Materials science, business.industry, EMI, Electromagnetic shielding, Electrical engineering, Electronics, Physics::Classical Physics, business, Electromagnetic interference, Magnetic flux, Magnetic field, Electromagnetic induction
Abstract

Electromagnetic railgun is a new concept weapon that uses electromagnetic force to launch projectiles. However, it differs from conventional guns in that the strong pulsed magnetic field of Tesla level will be produced in-bore during the launching process, which will cause the failure of electronic devices in the control circuit. In order to protect the circuit from electromagnetic interference (EMI), this paper designs a packaging method of combined shielding. The magnetic induction intensity on data storage system before and after shielding have been tested. The results show that this method can effectively restrain the EMI, and the electromagnetic shielding effectiveness (EMSE) can reach 8.5dB.

Published
2019

117. Entering the Era of Earth Observation-Based Landslide Warning Systems: A Novel and Exciting Framework

Author

Dai, Keren, primary, Li, Zhenhong, additional, Xu, Qiang, additional, Burgmann, Roland, additional, Milledge, David G., additional, Tomas, Roberto, additional, Fan, Xuanmei, additional, Zhao, Chaoying, additional, Liu, Xiaojie, additional, Peng, Jianbing, additional, Zhang, Qin, additional, Wang, Zheng, additional, Qu, Tengteng, additional, He, Chaoyang, additional, Li, Deren, additional, and Liu, Jingnan, additional

Published
2020
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122. “Bobbit Worm”‐Inspired Soft Adaptive Grasper with Self‐Generated Triboelectric Force Sensor

Author

Zhu, Zhisen, Dai, Keren, Wang, Mingchuan, Jiang, Liangjing, Bian, Leixiang, Zhang, Wenling, and Tian, Yu

Abstract

Soft actuators can realize delicate adaptive grasping of fragile and irregularly shaped objects, which are essential in biological and engineering systems. Yet, critical concerns in the frontier soft graspers are insufficient grasping ability and functional limitations. Here, we propose a Bobbit worm‐inspired multimodal‐sensing adaptive soft grasper (MSASG) enabled by harnessing the Miura‐origami skeleton integrated with self‐generated triboelectric force sensors (TFSs). The Miura‐origami skeleton endows the soft grasper a high grasping force while provides an energy‐efficient way to passively embrace an object without extra energy input. A multimodal TFSs with tactile sensing (TFS‐1) and pressure‐feedback (TFS‐2) functions is constructed by directly packaging a pyramid‐pattern elastic film on the Miura‐origami skeleton. The MSASG implement fast grasping or releasing action by evaluating pressures of various approaching prey, including hermit crabs, crickets, and beetle, etc. And its sensitivity greater than 0.18 V mN−1. In particular, the grasping performances and triboelectric sensing capacity can be optimized by modulating topological parameters (crease length, and surface film thickness, etc.), using a combination of theoretical modeling, finite element simulations, and experiments. The bionic design of soft graspers broadens the future applications for versatile human‐robot‐environment interaction scenarios, such as adaptive robots, reconfigurable architectures, medical devices, and deep‐sea explorations. A Bobbit worm‐inspired multimodal‐sensing adaptive soft grasper (MSASG) is proposed by employing Miura‐ori skeleton and self‐generated triboelectric force sensors (TFSs). Such a MSASG can successfully identify and swiftly capture diverse living organisms, including hermit crabs (24 mN), and crickets (10 mN), with an extremely low energy consumption of 0.514 mJ of the MCU circuit.

Published
2024
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134. Improved Energy Absorption Characteristics Based on Elastic Polymer-Modified Porous Material for Multiple Extreme Mechanical Impacts.

Author

Zhang, Jinming, Dai, Keren, Wang, Xiaofeng, Yu, Da, Yang, Benqiang, Zhang, He, and You, Zheng

Subjects
POROUS materials, IMPACT (Mechanics), ABSORPTION, COMPOSITE materials, ELECTRONIC equipment
Abstract

Energy absorbing materials are crucial for the protection of electronic devices in various applications. In particular, the protection of materials from multiple extreme mechanical impacts imposes stringent requirements on the characteristics of energy absorption and recoverability. In this paper, a novel design of composite material, elastic polymer-modified porous carbon, is proposed to meet such urgent requirements. At the micro level, the polymer fibers form an elastic skeleton in which porous carbon particles are enveloped. Due to such microstructure, the composite material exhibits excellent performance of energy absorption and recoverability simultaneously, which are validated via various experiments. Furthermore, the microphysical mechanism of its superior energy absorption characteristics is demonstrated theoretically. Additionally, the optimized mass proportions of the two composite phases are discussed. In general, this novel design of energy absorbing material improves the reliability of electronic devices and systems exposed to multiple extreme mechanical impacts. [ABSTRACT FROM AUTHOR]

Published
2020
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137. Solar thermal-driven capacitance enhancement of supercapacitors

Author

Yi, Fang, primary, Ren, Huaying, additional, Dai, Keren, additional, Wang, Xiaofeng, additional, Han, Yingzhou, additional, Wang, Kexin, additional, Li, Ke, additional, Guan, Baolu, additional, Wang, Jie, additional, Tang, Miao, additional, Shan, Jingyuan, additional, Yang, Hao, additional, Zheng, Mingsheng, additional, You, Zheng, additional, Wei, Di, additional, and Liu, Zhongfan, additional

Published
2018
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140. An adaptive and space-energy efficiency vibration absorber system using a self-sensing and tunable magnetorheological elastomer.

Author

Zhu, Zhisen, Wang, Ze, Dai, Keren, Wang, Xiaofeng, Zhang, He, and Zhang, Wenling

Abstract

Vibration monitoring and buffering is an important technical task in many industrial fields, such as bridges, machine tools and other specific applications. Recently, a magneto-rheological elastomer (MRE) has been utilized in an intelligent vibration absorber system with tunable stiffness, which can reversibly regulate its resonant frequency in real time to effectively prevent the resonance of the mechanical system. However, this MRE must be integrated with a vibrational sensor and equipped with an external magnetic field (e.g., electromagnetic coils or permanent magnets). Thus, the overall system is usually bulky and energy-intensive, which severely limits its broad application potential. In this work, we present an MRE-based tunable vibration absorber (MRE-TVA) with an elaborate 3-layered architecture integrated with a self-sensing triboelectric nanogenerator (TENG) sensor. The inner two-layer MRE structure exhibits variable stiffness, while the outer layer of the negative Poisson's ratio structure can confine the deformation of the inner MRE layers and form a contact-separation TENG sensor with the MRE, where the sensor can recognize external vibration information in a timely manner. In particular, the TENG sensor enables sensitive identification of the abnormal state of resonant excitation and other mechanical disturbances through dual logic judgment control based on vibration frequency and amplitude. For energy-space efficiency, a bistable permanent magnet controlled by a pulse current is integrated to generate a desirable magnetic field for modulation of the MRE stiffness. Compared with traditional electromagnetic coils, the energy and space utilization rates are increased by 94.25% and 75%, respectively. This combination of self-sensing and vibration damping systems achieves high energy-space efficiency, which will enable the intelligent health monitoring of bridges and other autonomous, smart, and long-term engineering tasks. [Display omitted] • An adaptive self-sensing vibration absorber system with 3-layered MRE architecture is proposed. • The MRE layer is confined by negative Poisson's ratio layer for real-time vibration monitoring. • The TENG sensor can sensitively identify and estimate vibration information. • A bistable permanent magnet controlled by pulse current is elaborately designed. [ABSTRACT FROM AUTHOR]

Published
2023
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150. A highly shape-adaptive, stretchable design based on conductive liquid for energy harvesting and self-powered biomechanical monitoring

Author

Yi, Fang, primary, Wang, Xiaofeng, additional, Niu, Simiao, additional, Li, Shengming, additional, Yin, Yajiang, additional, Dai, Keren, additional, Zhang, Guangjie, additional, Lin, Long, additional, Wen, Zhen, additional, Guo, Hengyu, additional, Wang, Jie, additional, Yeh, Min-Hsin, additional, Zi, Yunlong, additional, Liao, Qingliang, additional, You, Zheng, additional, Zhang, Yue, additional, and Wang, Zhong Lin, additional

Published
2016
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