皮秒脉冲细胞实验装置的设计与仿真优化

为在相同ps脉冲源输出电压下获得更高的电场强度以进行细胞实验,基于已有研究成果,设计了ps脉冲细胞实验装置,给出了信号不失真传输措施;并采用有限元法和CST建立了细胞实验装置的3维模型,综合考虑ps脉冲信号不失真传输、电场强度足够大以及电场均匀度良好3个重要指标后,对托针和电极池的相关参数进行了仿真优化。结果表明:采用所设计的实验装置传输电磁波时,其反射波幅值较小,并能产生强度较大的电场;托针直径对电极池中的电场分布具有影响,宽托针产生的电场更加均匀、反射波幅值更小;电极池中电场均匀度随极板厚度的减小先增大后减小。根据仿真结果,当托针直径取5 mm、极板厚度在0.66~0.70 mm之间时,电极池中的电场强度足够大且均匀度较好。     

基于非平衡Blumlein型多层微带传输线的高压纳秒脉冲发生器

为制作生物医学用小型化、紧凑型ns脉冲发生器,结合非平衡Blumlein型多层微带传输线和固态开关技术,研制了一台基于非平衡Blumlein型传输线的全固态高压纳秒脉冲发生器。通过波传播过程分析非平衡Blumlein型多层微带传输线方波形成原理;介绍了相关固态开关的控制时序及其"截波"策略,以此实现50~100 ns的方波脉冲脉宽可调;阐释了非平衡Blumlein型多层微带传输线系统的负载阻抗可变的相关原理;并研制了一台小型纳秒脉冲发生器以进行相关性能测试。最终,在50Ω负载下的纳秒脉冲电压参数:幅值0~2 k V可调、脉宽50~100 ns可调、重复频率0~1 k Hz可调,上升时间约20 ns;此外,测试了500Ω负载下输出的纳秒脉冲电压幅值约为充电电压的2倍。     

基于非接触式雷电流测量装置的新型线路分布式雷击故障定位方法

输电线路延绵数千里,传统人工巡线方式查找雷击故障点费时费力。因此基于非接触式雷电流测量装置,结合行波测距和小波包理论,提出了一种新型分布式雷击故障定位方法。根据三相电流行波极性差异,提出了绕击、雷击避雷线和杆塔的雷击类型识别方法;针对绕击情况,进行了雷击是否闪络的判断、雷击区间范围和闪络侧的确定,推导了不同监测区间段内线路雷击点和闪络点定位公式;利用小波包变换提取行波波前到达时间进行定位计算。经EMTP-ATP软件仿真验证,该方法能准确地进行输电线路雷击故障定位,雷击点和闪络点定位误差均0.4%,具有重要的应用价值。     

不可逆电穿孔微创消融肿瘤技术的研究进展

肿瘤愈发成为人类健康的主要威胁。传统的手术切除、化学治疗存在一定的禁忌症,且易对患者身心造成巨大的伤害,物理消融治疗就是在这种背景下提出的。为此,在简要介绍目前临床应用较广的几种物理消融技术的基础上,由电穿孔现象及其应用出发,着重介绍了率先由我国研究人员提出的不可逆电穿孔消融肿瘤技术的发展历程及研究进展。尽管不可逆电穿孔治疗肿瘤技术的机理尚未完全探明,但该技术由于具有治疗时间短、病人术后恢复快、对正常组织损伤小等优势,且可避免热消融损伤的缺憾,所以已展现出广阔的应用前景。然而,相对于国外的成果迅速转化的优势以及临床快速推进,国内的临床推进相对缓慢,但不可逆电穿孔消融肿瘤方法逐渐为我国工程专家和临床医生所接受,目前亟需汇集技术、临床及资金等各方面力量,将该技术尽快实现成果转化进而推广到临床以造福患者。     

Self-powered In-Phase Sensing and Regulating Mechanical System Enabled by Nanogenerator and Electrorheological Fluid

Mechanical system with adjustable stiffness and damping (ASAD) shows great potential in vibration suppression of aircraft, vehicle, precise instrument, etc. However, current ASAD systems consist of power, sensing, and controlling components, which bring huge challenges of system reliability and integrability, and critically limit its application diversity. Herein, we proposed the first strategy for regulating ASAD system that is system simplification, self-powered and no-delay by deeply coupling triboelectric nanogenerator (TENG) and electrorheological fluid (ERF). Under the time-varying mechanical triggering, the local and time correlated output of TENG instantaneously applied on the ERF regulates the entire mechanical system dynamically and “in-phase”. As an illustration, the resonance of a cantilever system is effectively suppressed naturally without complicated controlling strategy, and the vibration isolating efficiency reaches up to 85.2%. Finally, a mechanical transmission system is demonstrated utilizing a rotary TENG and ERF, excellent soft-start performance is enabled by this self-regulating ASAD strategy. This work may provide the opening arsenal of methodologies used in self-powered and self-regulating mechanical systems.     

Dual Mode TENG with Self-Voltage Multiplying Circuit for Blue Energy Harvesting and Water Wave Monitoring

As the most extensive natural energy on earth, ocean wave energy is regarded as a difficult energy to be fully and efficiently utilized because of its low frequency and multi-direction movement. Herein, a versatile blue energy triboelectric nanogenerator (VBE-TENG) fabricated by using dual-mode output terminals with charge excitation strategy is reported, which can harvest varying water-wave energy effectively. Benefiting from the rolling ball on a specific track and the compression rebound characteristics of a spring sheet steel, the carrier can be driven along a specific path through random ocean wave energy, and then the energy is converted into electricity by VBE-TENG. A high peak output power of 34.3 mW is obtained, 2.5 times as much as that of current highest record based on a device unit in blue energy TENG. In addition, the TENG can light 256 LEDs and continuously power commercial electronic devices in wave environments. The average peak voltage of contact-separation TENG is converted into virtual signal via Labview software to provide wave height monitoring as a self-powered sensing system. This work provides a new approach in blue energy TENG toward practical applications.     

High Durable Rotary Triboelectric Nanogenerator Enabled by Ferromagnetic Metal Particles as a Friction Material

Rotary sliding mode triboelectric nanogenerator (TENG) provides high efficiency, a continuous and high output strategy for harvesting low-frequency mechanical energy. However, poor durability owing to material abrasion during sliding restricts its practical application. Here, a novel ferromagnetic metal particle-based triboelectric nanogenerator (FMP-TENG) is proposed, which couples the unlimited point contact rolling motion of particles instead of planar contact of film to improve durability of TENG. Besides, due to the extensively enhanced contact area by ferromagnetic metal particles, FMP-TENG improves its electric output, achieving a charge density of 103 µC m⁻² and a peak power density of 400 mW m⁻² Hz⁻¹. After 10 000 cycle running-in, FMP-TENG exhibits excellent durability, which retains 97% of the output charge for 110 000 cycles. In addition, a metal powder mass sensor based on FMP-TENG is also designed, which can effectively detect mass change in ferromagnetic metal powder in a dynamic mechanical platform. A novel strategy is proposed here to solve the problem of durability of sliding TENG in practical applications.