NH4IO3晶体的压电性能

用干涉法测量了NH₄IO₃晶体的全部压电系数。结果为: d₃₁=35.2, d₃₂=23.4, d₃₃=55.9, d₂₄=-2.4, d₁₅=-9.5×10^-8 CGSE/DYN。 关键词：     

基于提升小波的压电埋入式超声信号的改进阈值降噪

在传统小波阈值降噪的基础上，提出了一种基于提升小波的改进阈值降噪方法，用于不同信噪比条件下实测压电传感器输出声信号的降噪，并与传统的硬、软阈值降噪方法进行对比。结果表明：该方法降低了硬、软阈值法降噪后信号的振荡，相比于硬阈值和软阈值降噪，信噪比 SNR值最多可提高58.32%，降噪均方差 MSE 值最多可降低64.28%。最后通过 Wigner-Ville 时频分布进一步验证了该方法的有效性。     

Phase Structures of （K0.48Na0.52）0.945Li0.055Sb0.05Nb0.95O3 Piezoceramics

The phase structures of lead-free （K0.48Na0.52）0.945Li0.055Sb0.05Nb0.95O3 piezoceramics are studied based on the measurements of ferroelectric and dielectric properties as well as the analyses of x-ray diffraction pattern and energy dispersive spectroscopy. The poled samples exhibit orthorhombic structure whereas the surface and interior for unpoled samples exhibit tetragonal and tetragonal-orthorhombic coexistent structures, respectively. These results are in agreement with the relative permittivity-temperature curves and demonstrate that phase transitions can be induced by Na volatilization and poling process. The remnant polarization Pr measured at 20°C increases continuously with the increase of electric field in the range of 2000-4000V/mm. This indicates that the polymorphic structure is more beneficial to the rotation or reorientation of dipoles than either the orthorhombic or the tetragonal structure. The randomly oriented domains may be the essential reason for the continuous rotation or reorientation and not good thermal stability.     

Local Piezoresponse and Thermal Behavior of Ferroelastic Domains in Multiferroic BiFeO3 Thin Films by Scanning Piezo-Thermal Microscopy

A dual probe, i.e., high resolution scanning piezo-thermal microscopy, is developed and employed to characterize the local piezoresponse and thermal behaviors of ferroelastic domains in multiferroic BiFeO3 thin films. Highly in- homogeneous piezoelectric responses are found in the thin film. A remarkably local thermal transformation across ferroelastic domain walls is clearly demonstrated by the quantitative 3w signals related to thermal conductivity. Different polarization oriented ferroelastic domains are found to exhibit different local thermal responses. The underlying mechanism is possibly associated with the inhomogeneous stress distribution across the ferroelastic domain wails, leading to different phonons scattering contributions in the BiFeO3 thin film.     

利用压电生物传感器研究核因子NF—κB与其特异结合DNA的相互作用

设计并合成了核因子NF-κB的特异结合DNA序列探针,在其5端巯基化修饰后固定在基频10 MHz的石英晶体金膜表面,构建压电DNA-蛋白质相互作用生物传感器,研究了传感器的响应特性及NF-κB的p65蛋白亚基与其特异DNA结合的亲和常数Ka.DNA探针浓度在0.25 ～2.0 μmol/L范围内,随着探针浓度的增加,传感器的响应频率逐渐增大,当探针浓度超过2.0 μmol/L时,传感器的响应频率反而降低;反应缓冲液镁离子浓度、pH对p65蛋白亚基与其特异DNA结合有影响,当MgCl2浓度为50 mmol/L、pH 7.5时,p65蛋白亚基与其特异DNA结合引起的传感器响应频率最大;在p65质量浓度为10 ～40 mg/L时,结合反应引起的频率变化与p65质量浓度呈线性相关,检测批内相对标准偏差(RSD)小于5%,批间RSD小于10%,最大结合量和结合常数Ka分别为(49.6±1.5) ng和(3.92±0.14)×106 L*mol-1.构建的压电DNA-蛋白质相互作用生物传感器具有结构简单、操作方便、不需标记、实时检测等优点,可直接用于核因子NF-κB与DNA的相互作用研究.     

串联式压电传感技术用于壳聚糖脱乙酰度测定及其对铜(Ⅱ)离子吸附的研究

基于酸碱滴定过程和金属离子吸附过程中的溶液电导率变化,首次将串联式压电石英晶体传感器(SPQC)用于壳聚糖脱乙酰度测定和壳聚糖对Cu2+的吸附特性考察.实验发现由滴定频率响应曲线测得的脱乙酰度与电位滴定法的测定值相近.用SPQC实时监测壳聚糖对Cu2+的吸附过程,通过比较频移响应曲线,考察了Cu2+初始浓度、吸附剂用量及脱乙酰度对壳聚糖吸附Cu2+性能的影响.结果表明,适当增加Cu2+浓度和吸附剂用量更利于壳聚糖对Cu2+的吸附,随着脱乙酰度的增加,壳聚糖对Cu2+的配位能力增强.     

Single-Electron Detachment for Ti-, Fe-, Co-, Ni-, and Cu-, in Collision with Ar

By using the micro-channel plate position sensitive detector with the delay-line anode we measure the single electron detachment cross sections for some transition elements in collision with Ar in the energy region 10-30 keV. These single electron detachment cross sections perform as velocity and electron affinity dependences. The experiments are carried out using the growth rate method.     

厚壁径向极化压电陶瓷薄圆环的研究

本文对厚壁径向极化压电陶瓷薄圆环进行了研究,得出了振子的谐振和反谐振频率的理论方程,并用有限元法分析了和实验测试了径向振动模态,给出了理论、有限元法和实验数据的一个对比。结果表明:本文的理论较为完善,对实际运用有一定的指导意义。     

有序结构氟聚合物压电驻极体的制备和压电性研究

描述了一种有序微孔结构压电聚合物功能膜的制备方法,利用模板的高度有序实现薄膜微孔结构的精确控制.将此制备方法用于氟聚合物压电驻极体薄膜的制备,通过扫描电子显微镜(SEM)对其微观结构的观察表明薄膜具有理想的有序结构.对氟聚合物压电驻极体压电性的研究则是利用正压电效应测量准静态压电系数d₃₃,通过等温衰减和压强依赖性的测量考察其压电性能.结果表明:有序结构氟聚合物压电驻极体的准静态压电系数d₃₃可高达300 pC/N;与无序结构氟聚合物     

双边缘测风激光雷达法布里-珀罗鉴频器控制方法

 提出一种双边缘测风激光雷达法布里-珀罗(F-P)干涉仪鉴频器的非线性比例-积分-微分(PID)控制方法。该方法利用发射激光在鉴频器校正通道的透过率作反馈进行F-P干涉仪鉴频器的稳定控制。首先给出F-P干涉仪鉴频器透过率的控制模型,由气压波动、温度变化和振动等引起的外界扰动被等效为施加在致动压电陶瓷上的扰动外力。为了进行扰动补偿,用新增的反正切函数设计了非线性PID控制器,提高了经典PID控制方法的反馈增益。仿真结果显示,与经典的PID控制相比,新的非线性控制方法可以使F-P干涉仪鉴频器在更短的时间达到稳定状态,并且稳态误差约减小到原来的1/20。