基于伪倒谱感觉加权滤波器的设计及应用

针对50Hz～7000Hz的宽带语音低频到高频的频谱倾斜现象严重问题,设计一个适用于宽带语音编码的感觉加权滤波器。该滤波器根据ISP伪倒谱与线性预测倒谱系数差进行设计,ISP伪倒谱是电抗函数自然对数一半取反z变换,其实质是一个多项式的倒谱。实验结果表明,该滤波器对改善宽带语音频谱倾斜问题具有较好的效果。

ISP与LSP的特性比较

介绍了ISP与LSP的定义,然后重点比较了ISP与LSP二者的相同特性和不同之处。通过仿真实验得到了ISP与LSP参数变化规律图,连续语音帧的ISP与LSP轨迹图,以及LPC谱包络与相应的ISFs、LSFs分布规律图等。实验结果表明,ISP与LSP都能够反映声道幅度谱中的共振峰特征,两者共同的顺序特性可使LPC滤波器的稳定性得到保证,且这两种参数的量化特性和内插特性均优于LPC系数,这为两种参数在语音编码及识别等领域的应用提供了理论基础。

In situ investigation of atmospheric corrosion behavior of PCB-ENIG under adsorbed thin electrolyte layer

The effects of relative humidity (RH) on a printed circuit board finished with electroless nickel immersion gold (PCB-ENIG) under an adsorbed thin electrolyte layer (ATEL) were investigated in situ via the measurement of cathodic polarization curves, electrochemical impedance spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy to clearly elaborate the corrosion behavior of PCB-ENIG in the atmospheric environment. Results indicated that the cathodic process of PCB-ENIG under ATEL was dominated by the reduction of dissolved oxygen, corrosion products, and H2O. The cathodic current density of PCB-ENIG increased progressively with increasing RH. Moreover, its cathodic current density in the solution was greater than that under ATEL. This result demonstrated that the diffusion process was not the controlling step during the limiting reduction of cathodic oxygen. When the polarization potentials were located in a more negative region, the cathodic polarization current density gradually decreased under 75% and 85% RH. Notably, the anodic process became the controlling step in the extremely thin liquid film during the remainder of the experiment.

包含寿命监测的在线燃料电池监测和运行状态识别(英文)

为故障诊断和健康度(SOH)估计,开发了一种不使用单一电池电压测量(CVM)的质子交换膜燃料电池(PEMFC) 的监测技术——"AVL THDA"。该技术运用谐波偏移、电抗谱技术,监测电池组的临界电压迁移,以保证可靠的运行状态;运行状态被在线评估,并被分成膜干涸、液体水滴和介质供应不足等几类。电池系统控制器可以立即启动计数测量,以防止电池的退化;考虑到了对于电池的长期影响,以及生命周期评估。该技术可以被集成到现有的燃料电池系统构件中,因此具有经济应用的前景。