To reduce the environmental pollution and meet the needs for wearable electronic devices, new requirements for electromagnetic interference(EMI) shielding materials include flexibility, biodegradability, and biocompat...To reduce the environmental pollution and meet the needs for wearable electronic devices, new requirements for electromagnetic interference(EMI) shielding materials include flexibility, biodegradability, and biocompatibility. Herein, we reported a polypyrrole-coated zein/epoxy(PPy/ZE) ultrafine fiber mat which was inherently biodegradable and skin-friendly. In addition, it could maintain its ultrafine fibrous structure after coating, which could provide the mat with mechanical compliance, high porosity, and a large specific area for high EMI shielding. With the assistance of the epoxide cross-linking, the breaking stresses of the PPy/ZE fiber mats could achieve 3.3 MPa and 1.4 MPa and the strains were 40.1% and 83.0% in dry and wet states, respectively, which met the needs of various wearable electronic devices. Along with the extension in the PPy treatment duration, more PPy was loaded on the fiber surfaces, which formed more integrated and conductive paths to generate increasing conductivities up to 401.76 S·m^(-1). Moreover, the EMI shielding performance was raised to 26.84 dB. The biobased mats provide a green and efficient choice for EMI shielding materials, which may be a promising strategy to address EMI problems in multiple fields.展开更多
To meet the demands for flexible electromagnetic interference(EMI)shielding materials,a type of conductive fabric is prepared by generating three-dimensional(3D)porous laser-induced graphene(LIG)in situ on the surface...To meet the demands for flexible electromagnetic interference(EMI)shielding materials,a type of conductive fabric is prepared by generating three-dimensional(3D)porous laser-induced graphene(LIG)in situ on the surface of the aramid fabric(AF)and then electroless plating copper.After LIG treatment,the porous AF demonstrates admirable conductivity due to the generation of graphene.The superior surface resistance of the conductive fabric can reach 1.57Ω/sq after copper deposition,and the average EMI shielding effectiveness(SE)can reach 34.3 dB in a frequency range of 8.2 to 12.4 GHz,with the EMW absorption accounting for about 80%.The proposed technology provides a new idea for preparation of flexible EMI shielding materials.展开更多
A systematic approach to the design of the conducted electromagnetic interference （EMI） filter of high-density plasma cutting power supply has been developed. Converter components have been accurately modeled, with ...A systematic approach to the design of the conducted electromagnetic interference （EMI） filter of high-density plasma cutting power supply has been developed. Converter components have been accurately modeled, with parasitic elements extracted to reveal their impacts on the EMI noises. Circuit simulations have been used to analyze and minimize the EMI noises. Conducted EMI noise measurement and filter design of this power supply have been achieved which successfully satisfy the FCC class B limits in the frequency range from 150 kHz to 30 MHz. The analyses and experimental results show that the designed filter guarantees that the required attenuation will be achieved.展开更多
针对复杂电子系统产生的传导EMI噪声,该文分别利用电偶极子模型、电路分析方法和散射参数方法提出了3种传导EMI噪声理论模型及其等效电路,包括因串扰引起的传导噪声模型,因接地不良引起的传导噪声模型,以及因PCB线缆阻抗失配引起的传导...针对复杂电子系统产生的传导EMI噪声,该文分别利用电偶极子模型、电路分析方法和散射参数方法提出了3种传导EMI噪声理论模型及其等效电路,包括因串扰引起的传导噪声模型,因接地不良引起的传导噪声模型,以及因PCB线缆阻抗失配引起的传导噪声模型。同时,还设计了一种串扰扼流圈以有效抑制因串扰引起的传导EMI噪声。实验结果表明,采用文中方法,某型商用车载导航和刷卡器能够通过GB 9254标准测试,噪声抑制效果分别可达44.8和29.28 dB V,从而验证了方法的有效性。展开更多
研究了电力线噪声分离网络技术,包括网络拓扑优化、分离网络元器件性能改善以及利用散射参数测量进行分离网络参数提取等。结果表明,上述技术可明显提高分离网络性能,如插损提高约3dB,噪声抑制比提高15dB以上。此外还分别完成了基于噪...研究了电力线噪声分离网络技术,包括网络拓扑优化、分离网络元器件性能改善以及利用散射参数测量进行分离网络参数提取等。结果表明,上述技术可明显提高分离网络性能,如插损提高约3dB,噪声抑制比提高15dB以上。此外还分别完成了基于噪声分离网络的开关电源电力线传导噪声和电力载波通信(power line communication,PLC)中的电力线辐射干扰噪声诊断抑制2个实验,验证了文中方法有效性。展开更多
基金Fundamental Research Funds for the Central Universities,China(No. 2232022D-13)Fundamental Research Funds of Shanghai Collaborative Innovation Center of High Performance Fibers and Composites (Province-M inistry Joint),China(No. X12812101/015)。
文摘To reduce the environmental pollution and meet the needs for wearable electronic devices, new requirements for electromagnetic interference(EMI) shielding materials include flexibility, biodegradability, and biocompatibility. Herein, we reported a polypyrrole-coated zein/epoxy(PPy/ZE) ultrafine fiber mat which was inherently biodegradable and skin-friendly. In addition, it could maintain its ultrafine fibrous structure after coating, which could provide the mat with mechanical compliance, high porosity, and a large specific area for high EMI shielding. With the assistance of the epoxide cross-linking, the breaking stresses of the PPy/ZE fiber mats could achieve 3.3 MPa and 1.4 MPa and the strains were 40.1% and 83.0% in dry and wet states, respectively, which met the needs of various wearable electronic devices. Along with the extension in the PPy treatment duration, more PPy was loaded on the fiber surfaces, which formed more integrated and conductive paths to generate increasing conductivities up to 401.76 S·m^(-1). Moreover, the EMI shielding performance was raised to 26.84 dB. The biobased mats provide a green and efficient choice for EMI shielding materials, which may be a promising strategy to address EMI problems in multiple fields.
基金Shanghai Sailing Program,Shanghai,China(No.22YF1400500)Fundamental Research Funds for the Central Universities,China(Nos.2232022D-11 and 22D128102/007)Shanghai Natural Science Foundation of Shanghai Municipal Science and Technology Commission,Shanghai,China(No.20ZR1401600)。
文摘To meet the demands for flexible electromagnetic interference(EMI)shielding materials,a type of conductive fabric is prepared by generating three-dimensional(3D)porous laser-induced graphene(LIG)in situ on the surface of the aramid fabric(AF)and then electroless plating copper.After LIG treatment,the porous AF demonstrates admirable conductivity due to the generation of graphene.The superior surface resistance of the conductive fabric can reach 1.57Ω/sq after copper deposition,and the average EMI shielding effectiveness(SE)can reach 34.3 dB in a frequency range of 8.2 to 12.4 GHz,with the EMW absorption accounting for about 80%.The proposed technology provides a new idea for preparation of flexible EMI shielding materials.
基金National Natural Science Foundation of China (No. 50477009)
文摘A systematic approach to the design of the conducted electromagnetic interference （EMI） filter of high-density plasma cutting power supply has been developed. Converter components have been accurately modeled, with parasitic elements extracted to reveal their impacts on the EMI noises. Circuit simulations have been used to analyze and minimize the EMI noises. Conducted EMI noise measurement and filter design of this power supply have been achieved which successfully satisfy the FCC class B limits in the frequency range from 150 kHz to 30 MHz. The analyses and experimental results show that the designed filter guarantees that the required attenuation will be achieved.
文摘针对复杂电子系统产生的传导EMI噪声,该文分别利用电偶极子模型、电路分析方法和散射参数方法提出了3种传导EMI噪声理论模型及其等效电路,包括因串扰引起的传导噪声模型,因接地不良引起的传导噪声模型,以及因PCB线缆阻抗失配引起的传导噪声模型。同时,还设计了一种串扰扼流圈以有效抑制因串扰引起的传导EMI噪声。实验结果表明,采用文中方法,某型商用车载导航和刷卡器能够通过GB 9254标准测试,噪声抑制效果分别可达44.8和29.28 dB V,从而验证了方法的有效性。
文摘研究了电力线噪声分离网络技术,包括网络拓扑优化、分离网络元器件性能改善以及利用散射参数测量进行分离网络参数提取等。结果表明,上述技术可明显提高分离网络性能,如插损提高约3dB,噪声抑制比提高15dB以上。此外还分别完成了基于噪声分离网络的开关电源电力线传导噪声和电力载波通信(power line communication,PLC)中的电力线辐射干扰噪声诊断抑制2个实验,验证了文中方法有效性。
