沥青基高比表面积活性碳的物理及化学结构

本文用ＡＳＡＰ２０００吸附仪测定了吸附性能优异的沥青基高比表面积新型活性碳（ＰＨＡＣ）的ＢＥＴ比表面积、用ＢＪＨ和ＤＲＳ法分析了其孔隙结构参数，用ＸＰＳ测定了ＰＨＡＣ的表面元素组成及含氧官能团，对ＰＨＡＣ的表面形态结构进行了ＳＥＭ和ＴＥＭ观察。研究表明：ＰＨＡＣ具有高度发达且均匀的微孔结构，其表面含有一定量的Ｃ－Ｏ－Ｃ、Ｃ－ＯＨ、Ｃ＝Ｏ、Ｏ＝Ｃ－Ｏ等多种类型的含氧官能团。     

Comparing ANN and GMM in a voice conversion framework

In this paper, we present a comparative analysis of artificial neural networks (ANNs) and Gaussian mixture models (GMMs) for design of voice conversion system using line spectral frequencies (LSFs) as feature vectors. Both the ANN and GMM based models are explored to capture nonlinear mapping functions for modifying the vocal tract characteristics of a source speaker according to a desired target speaker. The LSFs are used to represent the vocal tract transfer function of a particular speaker. Mapping of the intonation patterns (pitch contour) is carried out using a codebook based model at segmental level. The energy profile of the signal is modified using a fixed scaling factor defined between the source and target speakers at the segmental level. Two different methods for residual modification such as residual copying and residual selection methods are used to generate the target residual signal. The performance of ANN and GMM based voice conversion (VC) system are conducted using subjective and objective measures. The results indicate that the proposed ANN-based model using LSFs feature set may be used as an alternative to state-of-the-art GMM-based models used to design a voice conversion system.     

硬沥青改性聚苯乙烯材料的研究

采用熔融共混方法，用深度萃取脱油硬沥青和尤里卡沥青两种高软化点硬沥青材料，对聚苯乙烯(PS)进行改性。力学性能测试表明，硬沥青材料的加入能使PS的冲击强度得到不同程度的提高，但拉伸强度有一定程度下降；透射电镜微观证实，硬沥青在聚苯乙烯材料内主要以约100nm的微粒分布，均匀分散的硬沥青超胶束引起的锚钉效应是聚苯乙烯材料冲击强度提高的原因，但胶束及似晶结构不能有效分散开，导致其拉伸强度等得不到提高。     

不同炭化压力下沥青炭结构特性的研究

将高温煤沥青和浸渍剂沥青在不同压力下炭化，在2500℃下对所得沥青炭进行石墨化处理；测试了所得沥青炭的体积密度、开孔率；利用扫描电子显微镜（SEM）观察了所得沥青炭的显微结构；利用XRD检测了不同炭化压力所得沥青炭石墨化处理后的石墨化度。结果表明：随着炭化压力的增大．沥青炭的体积密度增大而开孔率减小；随着炭化压力的增大沥青炭显微结构有从流线型向镶嵌型和域型转变的趋势：流线型结构沥青炭石墨化度较高；沥青中QI组分也会影响沥青炭的显微结构。     

Catalytic hydrodechlorination of 1-chlorooctadecane, 9,10-dichlorostearic acid, and 12,14-dichlorodehydroabietic acid in supercritical carbon dioxide

Kinetic and thermodynamic analyses of catalytic hydrodechlorinations in supercritical carbon dioxide (SC-CO₂) were performed using 5% Pd supported on γ-Al₂O₃. The selected standard compounds used for the study represented chlorinated wood resins commonly found in pitch deposits; 1-chlorooctadecane (C₁₈-Cl), 9,10-dichlorostearic acid (Stearic-Cl₂), and 12,14-dichlorodehydroabietic acid (DHA-Cl₂). The reaction utilized isopropanol as a hydrogen donor. Pressure, temperature, and the concentrations of isopropanol and palladium were varied to study the effect of each parameter and to optimize the dechlorination yield. The reaction in SC-CO₂ was compared to the one in liquid solvents at atmospheric pressure. By applying a Langmuir–Hinshelwood kinetic model, the rate-determining step of the reaction was deduced to be adsorption of the chlorinated molecules on the palladium surface. The apparent activation energies of the reactions for C₁₈-Cl, Stearic-Cl₂, DHA-Cl₂ were 43±5, 40±7, and 135±7 kJ mol⁻¹, respectively, in SC-CO₂. The relatively high activation energy for DHA-Cl₂ was apparently due to structural differences from the other two compounds. The apparent activation energy of dechlorination of C₁₈-Cl in liquid isopropanol at atmospheric pressure was determined to be 35±3 kJ mol⁻¹, leading to the conclusion that the rate-determining step is the same for this compound in both fluid systems. The enthalpies of desorption of stearic acid and dehydroabietic acid were determined to be 18±2 and 12±2 kJ mol⁻¹, respectively. These values being less than half of the apparent activation energies of dechlorination of their corresponding chlorinated compounds indicates that desorption of the dechlorinated products is not the rate-determining step of the reaction. This was consistent with the conclusion that the rate-determining step is adsorption, on the understanding that the reaction mechanism is same in both fluid systems.     

三米数控车床实现螺补功能的原理及方法

在数控车削长丝杠时，采用螺距误差补偿的方法来补偿后面淬火工序所引起的螺距误差。文章介绍了该方法的补偿原理以及实际操作方法。     

一种改进的基音周期提取算法研究

现有的基音周期提取方法在准确度和稳健性上存在一定的局限性,很难准确地提取出信噪比较低的语音信号的周期.针对这一问题,提出一种基于小波变换的基音周期提取改进算法,将TEO(Teager Energy Operator)算子与二进小波变换结合起来,首先进行清浊判定,然后只对浊音帧采取多尺度小波分析提取周期,提出用幅度信息和出现概率信息校正二进小波模极大值间距,从而得到准确的周期.计算机仿真结果表明,与传统方法相比,不仅提高了处理效率,而且具有更高的精确度和稳定性.     

基音周期估计中倍数检验算法的研究

讨论了基于自相关函数法基音周期估计过程中的倍数检验和校正问题。自相关函数法是语音信号处理中的一种重要方法,但往往会把真实基音周期的倍数误判为真实的基音周期。为了防止误判,提出了倍数检验算法。实验表明:使用该算法,提高了基音周期估计的准确性,改善了基音周期轨迹的平滑度。     

Signal transformation and interpolation based on modified DCT synthesis

This paper proposes a novel signal transformation and interpolation approach based on the modification of DCT (Discrete Cosine Transform). The proposed algorithm can be applied to any periodic or quasi periodic waveform for time scale and/or pitch modification purposes in addition to signal reconstruction, compression, coding and packet lost concealment. The proposed algorithm has two advantages:

• (i) 

  Since DCT does not have the explicit phase information, one does not need the cubic spline interpolation of the phase component of the sinusoidal model.

• (ii) 

  The parameters to be interpolated can be reduced because of the energy packing efficiency of the DCT. This is particularly important if signal synthesis is carried out on a remote location from the transmitted parameters.

The results are presented on periodic waveforms and on speech signal in order to appreciate the fidelity of the proposed algorithm. In addition, the proposed method is compared with TD-PSOLA, sinusoidal model and phase vocoder algorithms. The results are presented in objective PESQ scores for time scale modification and output files are provided as supplementary material,¹ for subjective evaluation, for packet lost concealment. Results prove that the proposed modification of the DCT synthesis provides a favorable algorithm for specialists working in the signal processing area.     

音乐数据库的基于内容检索及一种基于ICA算法的按调查询系统的提出

目前音频数据库的研究相对于图象处于滞后,文中侧重音乐角度,结合MPEG标准和基于内容检索的应用,综述了音频检索的研究现状,分析了音频方面研究的特殊性和相关应用中的问题;并提出基于独立分量分析（ICA）的按调查询（QBH）的系统,较好地解决了特征提取中的鸡尾酒会效应问题。系统的查询结果置于三维声效环境中加速了查询。