Speech enhancement based on multitaper spectrum and psychoacoustical weighting rule

Multitaper spectrum has lower variance than the traditional periodogram. The noise spectrum and the noise to noisy signal spectrum ratio (NNSR) were estimated from the multitaper spectrum of the noisy signal; the pre-enhanced speech for calculating the noise masking threshold was obtained by the spectral amplitude subtraction method, whose gain is a function of NNSR; the final enhanced speech was obtained by suppressing the Fourier spectrum of the noisy speech with the psychoacoustical weighting rule incorporating the noise masking threshold. Because of the low variance feature of the multitaper spectrum, a modified offset formula was proposed to calculate the noise masking threshold, thus the reconstructed speech with this modification has an improvement in MBSD (Modified Bark Spectral Distortion). When a maximum limitation less than one to the psychoacoustical weighting rule is further proposed, the higher the input SNR (> 0 dB) is, the more improvement the segmental SNR and the overall SNR have. The informal listening tests show that there is little speech distortion for the enhanced speech processed by the proposed method, the background noise is reduced much and free of musical noise.     

二层信用策略下部分延期付款的库存模型

当前二层信用期相关文献考虑的都是零售商提供给其顾客相同的信用期,但现实中零售商往往会根据物品的种类不同提供给顾客不同的信用期.为研究此问题,建立了优化供货周期使零售商平均相关成本最小的库存模型,证明了最优供货周期的存在性,并给出实例加以说明.     

多星联合鲁棒性调度模型研究

在多星联合调度过程中,存在着很多不确定性因素,其中云层覆盖变化是主要的不确定性来源.本文针对考虑云层覆盖变化的多星联合调度问题,借鉴了连续函数的鲁棒性优化思想,提出了一种基于邻域的鲁棒性指标.在此基础上,建立了多星联合鲁棒性调度模型,给出了观测任务优先级的计算方法.实例研究表明,本文建立的模型能够在保证调度方案性能的基础上,获得鲁棒性强的调度方案.     

UV Photodissociation Dynamics of Nitric Acid： The Hydroxyl Elimination Channel

Sliced velocity mapping ion imaging technique was employed to investigate the dynamics of the hydroxyl elimination channel in the photodissociaiton of nitric acid in the ultraviolet region. The OH product was detected by （2＋1） resonance enhanced multiphoton ionization via the D^2∑^- electronic state. The total kinetic energy spectra of the OH＋NO2 channel from the photolysis of HONO2 show that both ：NO2（X2A1） and NO2（A2B2） channels are present, suggesting that both 1^1A″ and 2^1A″ excited electronic states of HONO2 are involved in the excitation. The parallel angular distributions suggest that the dissociation of the nitric acid is a fast process in comparison with the rotational period of the HNO3 molecule. The anisotropy parameter β for the hydroxyl elimination channel is found to be dependent on the OH product rotational state as well as the photolysis energy.     

含噻吩环的新推—拉型多环电光聚合物中间体的三阶非线性？…

以ＩＮＤＯ／ＳＣＩＯ方法的基础，利用完全态求和（ＳＯＳ）公式，计算了一系列新推－拉型多环电光聚合物间体的三阶非线性光学系数γ（－ω，ω，－ω，ω）、γ（０；０，０，０），研究了γ与分子骨架，给受取代基和噻吩环数目（共轭分子链长的关系）及其与外频率的关系，表明在链不十分长时，γ与链长的２．６９次方成正比。     

V-系统的快速变换算法

V-系统是L²[0,1]上的一类完备正交分段多项式函数系，由于其基函数的间断特性，在非连续信号的表达与分析上优势显著。然而，在目前的V-系统变换算法中，对于一个长度为N的信号，不仅需要事先生成并存储一个N阶的正交矩阵，而且其时间复杂度高达Ο(N³)。为实现对大规模数据的高效处理，从V-系统的多分辨率分析角度出发，设计并实现了V-系统的快速分解与重构算法，不仅无须存储额外信息，而且其时间复杂度仅为Ο(N)。测试结果表明，提出的快速算法能够满足大规模数据高效处理要求，为V-系统在更多领域的应用奠定了基础。     

具多滞量的非线性中立型差分方程的振动性定理

研究了一类较为广臣的具有多个滞量的非线性中立型差分方程的振动性,得到了该类方程振动的一个判定定理．