Processing and electromechanical properties of lanthanum-doped Pb(Zr,Ti)O<Subscript>3</Subscript> extruded piezoelectric fibres

This article describes the processing and characterisation of lanthanum-doped lead zirconate titanate (PLZT)-based ferroelectric fibres for composite transducer applications. X-ray diffraction of the extruded and sintered fibres indicated some lead loss during sintering; however, the fibres exhibited low porosity (1.54%), high maximum piezoelectric strain (4041 ppm) and relatively low coercive field (0.77 kV/mm). The low coercive field of the lanthanum-doped fibres may be advantageous in terms of facilitating polarization of the fibres in composite architectures.     

风力机参数的可辨识分析

风力机是风电机组吸收和转化风能的关键设备,准确的模型和参数是机组优化运行和控制的基础。文中基于风力机常用的高精度数学模型,运用计及实际运行工况的风力机的可测量量,进行参数的可辨识性理论分析,结果表明风力机的参数可辨识。     

A Soft Resistive Acoustic Sensor Based on Suspended Standing Nanowire Membranes with Point Crack Design

An artificial basilar membrane (ABM) is an acoustic transducer that mimics the mechanical frequency selectivity of the real basilar membrane, which has the potential to revolutionize current cochlear implant technology. While such ABMs can be potentially realized using piezoelectric, triboelectric, and capacitive transduction methods, it remains notoriously difficult to achieve resistive ABM due to the poor frequency discrimination of resistive‐type materials. Here, a point crack technology on noncracking vertically aligned gold nanowire (V‐AuNW) films is reported, which allows for designing soft acoustic sensors with electric signals in good agreement with vibrometer output—a capability not achieved with corresponding bulk cracking system. The strategy can lead to soft microphones for music recognition comparable to the conventional microphone. Moreover, a soft resistive ABM is demonstrated by integrating eight nanowire‐based sensor strips on a soft trapezoid frame. The wearable ABM exhibits high‐frequency selectivity in the range of 319–1951 Hz and high sensitivity of 0.48–4.26 Pa^?1. The simple yet efficient fabrication in conjunction with programmable crack design indicates the promise of the methodology for a wide range of applications in future wearable voice recognition devices, cochlea implants, and human–machine interfaces.     

自适应光电混合互连分流结构建模与性能分析

针对片上光电混合互连网络(hybrid optoelect ronic network-on-chip,HONoC)拥 塞控制与自适应能力差、无法实现光电联合仿真等问题,提出一种适用于可重构阵列处理器 的自适应光电混合互连分流结构,在此结构上设计了自适应分流路由算法与一种低损耗无阻 塞的5端口光路由器,并搭建了基于System verilog与Verilog的光电混合互连功能仿真与 性能统计模型。实验结果表明,在边缘节点阻塞的情况下所设计的路由算法避免拥塞能力平 均提升了17.5%,光路由器所需交叉波导与微环谐振器数量大幅减少,平均光路由器级插入 损耗仅为0.522 dB,所设计的光电混合互连性能统计模型具有支持 设计拓扑、结构和路由策 略等功能,并且可以对资源使用、功耗开销、插入损耗等性能进行统计分析。     

感应电机全阶状态观测器及其无源性转速控制

为了实现感应电机的高动态调速性能,针对电机的非线性本质,提出了一种基于全阶状态观测器及其转速自适应估算的感应电机无源性转速控制方案。在基于感应电机无源性与稳定性分析的基础上,设计了渐近稳定转矩跟踪无源性控制器。针对无源控制律所需转子电流难以观测的问题,提出了一种旋转坐标系下以转子电流和转子磁链为状态变量的全阶状态观测器,并应用该观测器对转速进行估算,实现了感应电机无速度传感器的无源性转速控制。仿真结果表明该控制方法易于实现,采用全阶观测器观测转子电流值和估算转速值更为准确,显著提高了感应电机的动静态性能。     

激光冲击强化对TC17微观组织和表面硬度的影响

为了研究激光冲击次数和冲击能量对TC17钛合金微观组织和表面硬度的影响,采用不同的工艺参量对TC17钛合金进行了激光冲击强化处理。TC17钛合金在激光冲击后,表面形成了剧烈塑性变形和高密度位错,冲击过程中位错发生增殖、塞积、缠结等现象,单脉冲冲击形成的微凹坑的深度最大可达21.4μm;脉冲能量为5J、搭接冲击次数从1次增加到4次时,材料的表面硬度相比母材的增幅分别为8.3%,17.2%,24.3%和24.5%;5J和7J冲击1次时,表面硬度相比母材增幅分别达8.3%和14.2%。结果表明,随着冲击次数和脉冲能量的增加,TC17材料表面硬度随之增加,激光冲击强化使材料表面产生高密度位错,这是其表面硬度增加的关键原因。     

基于随机网络演算的车联网边缘计算多跳任务卸载性能分析

车联网(IoV)边缘计算通过在网络边缘部署计算资源,可为车载用户提供低时延服务。该文通过随机网络演算(SNC)矩母函数(MGF)法分析车联网移动边缘计算的时延和数据积压性能。首先,分别对车辆高优先级和低优先级业务到达过程、单跳毫米波通信服务过程和边缘计算服务过程进行数学建模;其次,由服务级联定理获得不同优先级业务在多跳网络中的服务过程及其矩母函数表达式;接着,推导了车辆边缘网络不同优先级业务毫米波多跳通信任务卸载的时延和数据积压概率边界闭式解;最后通过蒙特卡罗仿真验证闭式解的准确性。     

利用水槽实验对不同流速下三角洲发育区别的探究

实验借助自制的小型水槽,探究了中等流速和高流速下三角洲发育的区别,结果表明:流速对于三角洲发育的影响主要体现在时间和规模上。不同流速下的发育过程均可划分为高建设期和低建设期。中等流速下三角洲在低建设期横向发育和斜向发育交替进行,而高流速下三角洲在低建设期先横向发育再斜向发育,并且高流速下三角洲砂体发育的时间较长。对于河道和朵叶体来说,中等流速下两者的数量要比高流速下两者的数量多。同一种流速下,不同位置的河道和朵叶体的规模存在区别,一般来说,发育在正前方的河道和朵叶体规模比两侧的规模大,但数量比两侧的要少。     

一种磁吸附式微小型惯性粘滑运动平台研究

在显微操作领域中,要求运动平台能在狭小空间中实现高精度的位姿调整,因此,该文提出了一款整体尺寸仅10 mm×10 mm×10 mm的惯性粘滑精密跨出度定位运动平台。该结构的设计采用将惯性部分与滑块部分集成为一体的设计方案,摩擦力使用磁铁来提供。对惯性粘滑运动平台中的柔性铰链进行尺寸优化,并使用有限元分析软件进行校核,验证理论分析的正确性。测试样机性能结果表明,水平方向最大运动速度为4.966 mm/s,竖直方向上运动速度可达2.1 mm/s,正、反向最大单步位移分别为2.984μm和2.349μm,步长重复性良好。实验证明,该样机具有体积小,运动速度快,步长重复性稳定等特点,适用于狭小空间内的高精度运动。     

Surface Reconstruction Engineering with Synergistic Effect of Mixed-Salt Passivation Treatment toward Efficient and Stable Perovskite Solar Cells

Surface passivation treatment is a widely used strategy to resolve trap-mediated nonradiative recombination toward high-efficiency metal-halide perovskite photovoltaics. However, a lack of passivation with mixture treatment has been investigated, as well as an in-depth understanding of its passivation mechanism. Here, a systematic study on a mixed-salt passivation strategy of formamidinium bromide (FABr) coupled with different F-substituted alkyl lengths of ammonium iodide is demonstrated. It is obtained better device performance with decreasing chain length of the F-substituted alkyl ammonium iodide in the presence of FABr. Moreover, they unraveled a synergistic passivation mechanism of the mixed-salt treatment through surface reconstruction engineering, where FABr dominates the reformation of the perovskite surface via reacting with the excess PbI₂. Meanwhile, ammonium iodide passivates the perovskite grain boundaries both on the surface and top perovskite bulk through penetration. This synergistic passivation engineer results in a high-quality perovskite surface with fewer defects and suppressed ion migration, leading to a champion efficiency of 23.5% with mixed-salt treatment. In addition, the introduction of the moisture resisted F-substituted groups presents a more hydrophobic perovskite surface, thus enabling the decorated devices with excellent long-term stability under a high humid atmosphere as well as operational conditions.