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...     

煤焦油精制软沥青中氮、硫的分布和热稳定性的分析

以高温煤焦油为原料制备煤精制软沥青及其族组成,再炭化制备半焦。通过元素分析和红外光谱分析杂原子氮、硫的分布和热稳定性。     

一种特征波提取速率自适应的波形内插语音编码方案

该文提出了一种特征波形提取速率自适应于输入语音帧特性的波形内插编码方案。基于双加权长时预测增益最大原则并利用前向基音判决实现了较为可靠的基音周期估计算法,用基音周期、浊音度和波表面平坦度决定波形提取速率以及SEW(Slowly Evolving Waveform)和REW(Rapidly Evolving Waveform)的更新速率。实验证明,该文提出的波形内插(WI)编码算法相比固定波形提取速率的WI算法在平均码率和计算复杂度上均有一定程度的降低,且合成语音质量明显优于4.8kbps的CELP语音编码算法。     

基于语音谐波结构的鲁棒特征参数及其在说话人识别中的应用

通过对纯净语音及含噪语音短时谱的分析比较,提出了一种基于基音频率及其谐波结构的新的语音特征参数。实验表明,与传统的倒谱特征相比,新特征对加性白噪声相对较不敏感,在闭集文本无关说话人识别中,新特征可以在加性白高斯噪声环境下提高系统的说话人识别率。