Experimental study on phase perception in speech

As the human ear is dull to the phase in speech, little attention has been paid to phase information in speech coding. In fact, the speech perceptual quality may be degenerated if the phase distortion is very large. The perceptual effect of the STFT (Short time Fourier transform) phase spectrum is studied by auditory subjective hearing tests. Three main conclusions are (1) If the phase information is neglected completely, the subjective quality of the reconstructed speech may be very poor; (2) Whether the neglected phase is in low frequency band or high frequency band, the difference from the original speech can be perceived by ear;(3) It is very difficult for the human ear to perceive the difference of speech quality between original speech and reconstructed speech while the phase quantization step size is shorter than π/7.     

单瞬时态Q—矩阵的特征

设Ｑ为单瞬时态拟Ｑ－矩阵，在本文中，我们给出了准Ｂ型Ｑ过程存在的充要条件，特别，当Ｑ为单瞬时准保守时，我们得到了Ｑ为Ｑ－矩阵的充要条件。     

Refractive Interstellar Scintillation for Flux Density Variations of Two Pulsars

The flux density structure functions of PSRs BO525 21 and B2111q-46 are calculated with the refractive interstellar scintillation (RISS) theory. The theoretical curves are in good agreement with observations [Astrophys.J. 539 (2000) 300] (hereafter S2000). The spectra of the electron density fluctuations both are of Kolmogorov spectra. We suggest that the flux density variations observed for these two pulsars are attributed to refractive interstellar scintillation, not to intrinsic variability.     

变保费率Cox风险模型的研究

研究了当保费率随理赔强度的变化而变化时C ox风险模型的折现罚金函数,利用后向差分法得到了折现罚金函数所满足的积分方程,进而得到了破产概率,破产前瞬时盈余、破产时赤字的各阶矩所满足的积分方程.最后给出当理赔额服从指数分布,理赔强度为两状态的马氏过程时破产概率的拉普拉斯变换,对一些具体数值计算出了破产概率的表达式.     

快中子物理和实验技术研究

综述近年来在北师大低能所的国内第一台脉冲化高压倍加器上开展的快中子物理，及有关的实验和数据处理技术研究. The study on fast neutron physics and relative technique of experiment and data analysis made at a pulsed neutron generator in Beijing Normal University during recent yeras is introduced.     

发光二极管测试技术和标准

文章从发光二极管的空间能量分布和光谱能量分布两个方面叙述了光和辐射参数测试的原理和方法．讨论了辐射通量和光通量的基本概念、测量方法及相互之间的关系．在实际应用中，发光二极管的发光强度和辐射功率及他们的空间分布是常需要测量的参数．文章从基于人类视觉特性的色度学原理出发，讨论了发光二极管的光谱能量分布和重要的色度学参数以及相应的测试标准问题．     

一类含瞬时态的Q—矩阵

设■其中0≤b_1<∞,0≤q_1<∞,i≥1。本文分别给出了Q为Q-矩阵及诚实Q-矩阵的充要条件,并证明了,如果Q是Q-矩阵,则存在无穷多个诚实Q-过程,对于含有限多个瞬时态的对角形Q-矩阵,也得到类似结果。本文所构造的Q-过程可以用其拉氏变换明显表达出来。     

三相感应电动机的新型微机直接转矩控制系统

 随着电力电子学和微机的发展,变频变压交流电动机传动系统在很多工业部门中的应用日益增加,而这些新的应用需要简单的控制交流电动机的方法。众所周知,交流电动机的速度控制,因其与电压、频率和转矩控制有关,而比直流电动机的速度控制困难。     

HL-2A装置偏滤器位形下氢和碳的粒子通量比

等离子体-壁相互作用通过各种机制释放粒子，主等离子体中杂质的数量限制了装置的性能。要深入认识杂质释放的机制，测量和分析粒子通量非常重要。文献[1]中详细描述了用光谱方法测量托卡马克等离子体中来自局部表面的向内的杂质通量，文献[2]报道了用这种方法测定ASDEX装置ICRF加热条件下向内的铬的通量。