基于单DSP的VoIP模拟电话适配器研究与实现

提出和实现了一种新颖的基于单个通用数字信号处理器(DSP)的VoIP模拟电话适配器方案。DSP的I/O和存储资源非常有限，通常适于运算密集型应用，不适宜控制密集型应用[5]。该系统高效利用单DSP的I/O和片内外存储器资源，采用μC/OS-II嵌入式实时操作系统，支持SIP和TCP-UDP/IP协议，通过LAN或者宽带接入，使普通电话机成为Internet终端，实现IP电话。该系统软硬件结构紧凑高效，运行稳定，成本低，具有广阔的应用前景。     

高精度数字跟踪式压电陶瓷驱动电源设计

设计了一种数字跟踪式复合结构的压电陶瓷驱动电源。采用数字式自适应信号源,驱动高精度运放OP07和高压大电流运放PA04组成复合式放大器,通过合理的相位补偿、保护电路设计和散热计算,实现高精度低漂移的压电陶瓷驱动。     

基于SPI总线的DSP与音频编解码芯片的接口设计

语音信号处理系统中,DSP与音频编解码芯片存在数据格式与速度不匹配的问题,使接口成为设计的关键。针对该问题提出了一种基于SPI总线的DSP与音频编解码芯片的接口设计方法,介绍了接口的关键组成部分。此方法在FPGA上进行了实现,已应用于SuperV DSP处理器的音频处理系统中。     

Integration of beamforming and uncertainty-of-observation techniques for robust ASR in multi-source environments

This paper presents a new approach for increasing the robustness of multi-channel automatic speech recognition in noisy and reverberant multi-source environments. The proposed method uses uncertainty propagation techniques to dynamically compensate the speech features and the acoustic models for the observation uncertainty determined at the beamforming stage. We present and analyze two methods that allow integrating classical multi-channel signal processing approaches like delay and sum beamformers or Zelinski-type Wiener filters, with uncertainty-of-observation techniques like uncertainty decoding or modified imputation. An analysis of the results on the PASCAL-CHiME task shows that this approach consistently outperforms conventional beamformers with a minimal increase in computational complexity. The use of dynamic compensation based on observation uncertainty also outperforms conventional static adaptation with no need of adaptation data.     

移动互联网用户价值动态分析模型

现有的用户价值分析模型在分析移动互联网用户价值时有一定的局限性。针对移动互联网用户,提出一种用户价值动态分析模型,通过对用户会话价值的分析,使用一种增量计算的方法。动态、真实的反映出用户的价值。     

阵列声成像系统的设计

提出了一种阵型优化的平面传声器阵列。基于这种优化的阵型,研制了一种声源定位系统,也称阵列声成像系统。该系统硬件上由传声器,数据采集,信号处理和显示控制四个模块组成。软件上,开发了基于数字信号处理器的声源定位程序和基于MFC的显控界面,实现了很好的人机交互。通过半消声室的实验分析,证明了该阵列声成像系统在声场可视化应用方面的有效性。     

一种支持一般访问结构的可验证短秘密共享方案

数据分离是构建可生存存储系统的关键技术,本文在分析现有数据分离方案的特性及不足的基础上,提出一种支持一般访问结构可验证短秘密共享数据分离方案。该方案生成的数据片段由密文分量和密钥分量组成,首先对原始数据进行加密并采用纠删编码分离密文,然后采用一种改进的可验证秘密共享算法分离密钥,且密钥的分离过程须依赖于密文分量。相比现有的工作,本方案在空间开销、保密性及可验证性方面均获得了较高的性能,并支持一般访问结构。     

组合阵栅瓣抑制方法研究

随着水声探测频带延伸至低频/甚低频段,目前大孔径拖线阵声纳需要处理超过10倍频程的宽带信号.稀疏阵列虽能以较小系统工程代价获得足够窄的波束扫描宽度,但会产生严重的栅瓣效应,使弱目标检测变得困难.为了抑制强十扰的栅瓣效应对弱目标检测的影响,本文将MVDR方法应用于宽带组合阵处理,有效抑制了栅瓣模糊,扩展了处理频带.理论分析表明组合阵MVDR方法与CBF相比,具有显著的栅瓣抑制能力,通过仿真分析和海试数据分析验证了该方法的有效性.     

Identification of ARMA models using intermittent and quantized output observations

This paper studies system identification of ARMA models whose outputs are subject to finite-level quantization and random packet dropouts. Using the maximum likelihood criterion, we propose a recursive identification algorithm, which we show to be strongly consistent and asymptotically normal. We also propose a simple adaptive quantization scheme, which asymptotically achieves the minimum parameter estimation error covariance. The joint effect of finite-level quantization and random packet dropouts on identification accuracy are exactly quantified. The theoretical results are verified by simulations.     

Calcined and natural frustules filled epoxy matrices: The effect of volume fraction on the tensile and compression behavior

The effects of calcined diatom (CD) and natural diatom (ND) frustules filling (0–12 vol.%) on the quasi-static tensile and quasi-static and high strain rate compression behavior of an epoxy matrix were investigated experimentally. The high strain rate testing of frustules-filled and neat epoxy samples was performed in a compression Split Hopkinson Pressure Bar set-up. The frustules filling increased the stress values at a constant strain and decreased the tensile failure strains of the epoxy matrix. Compression tests results showed that frustules filling of epoxy increased both elastic modulus and yield strength values at quasi-static and high strain rates. While, a higher strengthening effect and strain rate sensitivity were found with ND frustules filling. Microscopic observations revealed two main compression deformation modes at quasi-static strain rates: the debonding of the frustules from the epoxy and/or crushing of the frustules. However, the failure of the filled composites at high strain rates was dominated by the fracture of epoxy matrix.