不同喹啉不溶物的特性及对中间相转化过程的影响

采用￣１３Ｃ－ＮＭＲ、ｘ－ｒａｙ衍射、扫描和透射电镜研究了二种ＱＩ──原生ＱＩ、次生ＱＩ（喹啉不溶物）结构，并通过热转化试验考察了它们对中间相热转化过程的影响。结果表明，原生ＱＩ是由炭黑状固体小圆球组成，并包含有煤粉、焦粉等夹杂物，属非晶态混和物。它在中间相转化过程中，促使中间相小球体较早生成，并阻碍中间相球体融并，导致中间相热转化最终固体产物的镶嵌结构生成。次生ＱＩ微晶排列有序性较好，属中间相组织或中间相前躯体，对中间相的成长过程有利。     

The Effect of Cricothyroid Muscle Action on the Relation Between Subglottal Pressure and Fundamental Frequency in an In Vivo Canine Model

The relation between subglottal pressure (P_s) and fundamental frequency (F₀) in phonation was investigated with an in vivo canine model. Direct muscle stimulation was used in addition to brain stimulation. This allowed the P_s-F₀ slope to be quantified in terms of cricothyroid muscle activity. Results showed that, for ranges of 0–2 mA constant current stimulation of the cricothyroid muscle, the P_s-F₀ slope ranged from 10 Hz/kPa to 60 Hz/kPa. These results were compared to similar slopes obtained in a previous study on excised larynges in which the vocal fold length was varied instead of cricothyroid activation. A physical interpretation of the P_s-F₀ slope is that the amplitude-to-length ratio of the vocal folds decreases with CT activity, resulting in a smaller time-varying stiffness. In other words, there is less dependence of F₀ on amplitude of vibration when the vocal folds are long instead of short.     

Structural Analysis of Bisphenol-A and its Methylene,Sulfur, and Oxygen Bridged Bisphenol Analogs

The molecular structures of bisphenol-A, C(CH₃)₂(p-C₆H₄OH)₂ (monoclinic, P2₁/n, a = 11.1940(6) Å, b = 18.738(1) Å, c = 17.8623(9) Å, β = 100.571(1)°), its methylene (CH₂) and heteroatom (S, O) bridged analogs, CH₂(p-C₆H₄OH)₂ (monoclinic, P2₁/n, a = 5.4351(1) Å, b = 20.7895(3) Å, c = 8.8432(1) Å, β = 93.419(1)°), S(p-C₆H₄OH)₂ (monoclinic, P2₁/n, a = 5.5115(1) Å, b = 21.0666(2) Å, c = 8.6917(1) Å, β = 92.962(1)°) and O(p-C₆H₄OH)₂ (orthorhombic, Pbcn, a = 5.2745(5) Å, b = 8.2724(8) Å, c = 22.085(2) Å), have been determined by X-ray diffraction at 115 K, revealing structural differences in the series of compounds. The results show that the C_aryl–X_bridge–C_aryl angles (X_bridge = C(CH₃)₂, CH₂, S, O) span a range greater than 14°. The dihedral angle between the planes of the hydroxyphenyl groups also varies according to the identity of the bridging group, varying from 67.24(2)° in S(p-C₆H₄OH)₂ to 85.82(4)° in C(CH₃)₂(p-C₆H₄OH)₂. In addition, the pitch angle, which more accurately describes the propeller-like nature of these bisphenolic compounds, varies from 39.88(3)° in S(p-C₆H₄OH)₂ to 59.62(7)° in C(CH₃)₂(p-C₆H₄OH)₂. Ab initio electronic structure calculations predict very similar bond lengths and angles to those observed crystallographically; however, the predicted dihedral angles and pitch angles are quite different, suggesting that these features are greatly influenced by crystal packing.     

Mandarin tone recognition based on wavelet transform and hidden Markov modeling

This paper presents a method of tone recognition for Mandarin speech by using combination of wavelet transform and hidden Markov modeling techniques. A pitch detector based on singularity detection and multi-resolution analysis of wavelet transform is employed for estimation of pitch periods, and hidden Markov modeling with partition Gaussian mixtures probability density function is used for the tone recognition. The algorithm can provide recognition accuracy of 97.22% and 94.47% for speaker-dependent and speaker-independent tone recognition, respectively.     

基于B-样条子波变换的MBE语音模型分析算法改进

首先对 ＭＢＥ模型分析算法的复杂度进行了深入的分析,认为原算法中的双闭环基音搜索结构有很大的改进余地．为此提出了一种基于Ｂ－样条二进离散子波变换（Ｂ—ＳＤｙＷＴ）基音检测法的改进ＭＢＥ模型分析算法。其关键在于利用Ｂ－ＳＤｙＷＴ基音检测原理将这种双闭环搜索算法改造成先开环后闭环的结构。理论分析可以说明这种改造可以大幅度地降低基音搜索的复杂度,而不降低其性能。通过仿真实验,我们对改进前、后的ＭＢＥ模型基音搜索算法的复杂度、准确度以及抗噪声能力等方面作了一个全面的对比分析。得出这样的结论：改进算法与原算法相比,各项性能均不低于原算法甚至有所改善,特别是证实了理论分析中的复杂度降低作用。     

A method of torque control for independent wheel drive vehicles on rough terrain

Our previous research has revealed that, for vehicles with independently driven wheels, a torque distribution based on the ratio of the vertical load of each wheel to the total vehicle load is efficient for driving on flat ground. In this research, this method of torque distribution was extended to electric off-road vehicles driving on rough ground. In order to examine the driving efficiency of these vehicles, a numerical vehicle model was constructed in the pitch plane. Simulations using the numerical vehicle model on rough ground were conducted with a proposed torque distribution and control method. The numerical results from these simulations were compared with those of a conventional vehicle to evaluate the driving efficiency and trafficability on ground with various profiles. A comparison between the simulations demonstrated that the proposed method of torque distribution to the front and rear wheels based on the ratio of the vertical load is efficient for driving on rough ground.     

A novel pitch control system for a wind turbine driven by a variable-speed pump-controlled hydraulic servo system

The paper aims to develop a novel pitch control system for a large wind turbine driven by a variable-speed pump-controlled hydraulic servo system. To perform practical pitch control experiments, a full-scale test rig of the hydraulic pitch control system for a 2 MW wind turbine’s blade, including a novel pitch control mechanism, a variable-speed pump-controlled hydraulic servo system, a disturbance system and a PC-based control system, is designed and set up. The variable-speed pump-controlled hydraulic servo system, containing an AC servo motor, a constant displacement hydraulic piston pump two differential hydraulic cylinders and hydraulic circuits, achieved high response and high energy efficiency, so it is suitable for wind turbine applications. Besides, to implement the pitch control in the proposed novel pitch control system, an adaptive fuzzy controller with self-tuning fuzzy sliding-mode compensation (AFC-STFSMC) is developed to design the pitch controller. Finally, the developed variable-speed pump-controlled hydraulic servo system was built and verified for the path tracking control and path-positioning control of the pitch control of the wind turbines by practical experiments in a full-scale test rig under different path profiles, load torques, and random wind speeds.     

影响BGA封装焊接技术的因素研究

虽然表面贴装制造工艺已经纯熟,但是随着BGA封装的广泛应用以及焊球间距的逐步减小,给表面贴装制造工艺带来了新的挑战.基于BGA封装在表面贴装技术焊接中的应用,从印制电路板焊盘设计、印制电路板板材选取和保护、BGA封装选取和保护、印刷工艺、回焊炉温度曲线设定与控制等方面,阐述了影响BGA封装焊接技术的各个因素,进而提升B...     

改进汉语数码语音识别中的语音特征提取性能

汉语数据码语音识别中存在三种与语音特征提取性能有关的语音混淆。     

The role of pitch in the discrimination of voice quality

Pitch is an important attribute of a musical sound. With it the melody of a song is established. With it the beauty of a voice is showcased. But how does pitch affect the perception of voice? Is it used to help to distinguish among voices or does it merely exist in the background, affecting the fine details of a voice but not radically altering the voice? The purpose of this paper is to review some of the evidence on the role of pitch in the perception of voice quality; specifically for the discrimination of one voice quality from another. The objective of the discussion is to understand how pitch affects our perception of voice quality and its importance to the perception of musical sound.