基于动态数量高斯分量的关键词识别系统

提出了一种利用动态数量高斯分量拟合不同音素,利用拟合的音素组合作为补白参与语音关键词识别系统二次判决的方法.首先分析了为音素分配动态的高斯分量数量来训练音素模型的可行性;进而寻找能够准确描述音素且保证描述在不同音素之间有足够区分度的高斯分量个数;利用得到的音素与高斯分量数量的关系训练动态高斯添加的音素隐马尔科夫模型,利用模型的排列组合作为补白为语音关键词识别系统添加第二次判决来减小系统错误识别率.实验表明,利用这种方法进行语音关键词系统二次判断,能将原系统错误率降低至14.79%.

基于混合高斯模型的相关非高斯输入变量随机潮流计算

提出一种考虑输入变量相关性的随机潮流计算方法.该方法针对系统中的非高斯输入变量,建立其混合高斯模型(GMM).在此基础上,引入高斯分量组合算法(GCCM),通过多次加权最小二乘计算(WLS)直接求得输出变量的概率分布.研究限制GMM中高斯分量个数的约简方法,以减少WLS运算次数.对IEEE-30节点系统的仿真和误差分析表明,GMM具有拟合精度高、适用性广的特点.所提方法与MCS的计算结果基本一致,但计算效率有了显著提高,并且算法的速度和精度与WLS运算次数有关.

基于GRD-Hough变换的多高斯源盲分离算法

盲源分离有一个重要假设:源信号最多只含一个高斯信号。否则,基于统计量的盲分离算法性能会恶化。本文从广义矩形分布出发,通过把时域中的一维信号映射到二维的时-频表示来提供信号的频谱内容随时间变化的信息,并对时频谱进行Hough变换处理,利用不同高斯源的时频分布差异性,避开统计量提出了一种能分离多个高斯源的盲分离算法,扩展了盲源分离的应用领域。

一种渐进剥离与整体拟合的子波形提取方法

针对全波形分解中弱子波形提取困难以及子波形提取精度不高的难点,提出了一种在总波形约束下的子波形渐进剥离分解方法,通过计算回波局部最大值来确定高斯分量的峰值和中心位置以及利用高斯拐点匹配确定左、右拐点求取半宽值,将剩余波形重复迭代剥离直至子波形的最大峰值小于振幅阈值,渐进获取各子波形参数的初值,进而在总波形约束下实现各子波形的整体拟合与参数精化。通过对ICESat-GLAS回波信号进行波形分解表明,该方法能有效提取弱子波形,与3种传统的波形分解方法相比,提取子波形的数目和参数初值合理,整体拟合后的均方根误差分别下降75%、66.85%和64.1%。

Attenuation compensation in multicomponent Gaussian beam prestack depth migration

Gaussian beam prestack depth migration is an accurate imaging method of subsurface media. Prestack depth migration of multicomponent seismic data improves the accuracy of imaging subsurface complex geological structures. Viscoelastic prestack depth migration is of practical significance because it considers the viscosity of the subsurface media. We use Gaussian beam migration to compensate for the attenuation in multicomponent seismic data. First, we use the Gaussian beam method to simulate the wave propagation in a viscoelastic medium and introduce the complex velocity Q-related and exact viscoelastic Zoeppritz equation. Second, we discuss PP- and PS-wave Gaussian beam prestack depth migration algorithms for common-shot gathers to derive expressions for the attenuation and compensation. The algorithms correct the amplitude attenuation and phase distortion caused by Q, and realize multicomponent Gaussian beam prestack depth migration based on the attenuation compensation and account for the effect of inaccurate Q on migration. Numerical modeling suggests that the imaging resolution of viscoelastic Gaussian beam prestack depth migration is high when the viscosity of the subsurface is considered.

Error Thresholds in Single-Peak Gaussian Distributed Fitness Landscapes

Based on the Eigen and Crow-Kimura models with a single-peak fitness landscape, we propose the fitness values of all sequence types to be Gausslan distributed random variables to incorporate the effects of the fluctuations of the fitness landscapes （noise of environments） and investigate the concentration distribution and error threshold of quasispecies by performing an ensemble average within this theoretical framework. We find that a small fluctuation of the fitness landscape causes only a slight change in the concentration distribution and error threshold, which implies that the error threshold is stable against small perturbations. However, for a sizable fluctuation, quite different from the previous deterministic models, our statistical results show that the transition from quasi-species to error catastrophe is not so sharp, indicating that the error threshold is located within a certain range and has a shift toward a larger value. Our results are qualitatively in agreement with the experimental data and provide a new implication for antiviral strategies.

Longitudinal Magnetoresistance and ＂Chirar＇ Coupling in Silver Chalcogenides

A complex longitudinal magnetoresistance （MR//） effect in the non-stoichiometric silver chaJcogenides （include the silver selenide and telluride） has been found, however the mechanism for the MR// effect is not clear now. In this work, a new random resistor network for MR// effect is proposed based on the experimental observation. The network is constructed from six-terminal resistor units and the mobility of carries within the network has a Gaussian distribution. Considering the non-zero transverse-longitudinal coupling in materials, the resistance matrix of the six- terminal resistor unit is modified. It is found that the material has the ＂chiral＂ transverse-longitudinal couplings, which is suggested a main reason for the complex MR//effect. The model predictions are compared with the experimental results. A three dimension （3D） visualization of current flow within the network demonstrates the ＂current jets＂ phenomenon in the thickness of materials dearly.

An Array Extension Method in a Noisy Environment

An array extension method in a noisy environment was proposed to improve angular resolution and array gain. The proposed method combines the FOC （fourth-order cumulants） technique with the ETAM （extended towed array measurements） method to extend array aperture and suppress Gaussian noise, First, successive measurements of a virtual uniform linear array were constructed by applying lburth-order cumulants to measurements of uniform linear array; Gaussian noise in these measurements was also eliminated. Then, the array was extended by compensating phase differences using the ETAM method, Finally, the synthetic aperture was extended further by the fourth-order cumulants technique. The proposed FOC-ETAM-FOC method not only improves angular resolution and array gain, but also effectively suppresses Gaussian noise. Furthermore, it inherits the advantages of the ETAM method. Simulation results showed that the FOC-ETAM-FOC method achieved better angular resolution and array gain than the ETAM method. Furthermore this method outperforms the ETAM method in Gaussian noise environment.

Deterministic Quantum Key Distribution Using Gaussian-Modulated Squeezed States

A continuous variable ping-pong scheme, which is utilized to generate deterministic private key, is proposed. The proposed scheme is implemented physically by using Ganssian-modulated squeezed states. The deterministic char- acteristic, i.e., no basis reconciliation between two parties, leads a nearly two-time efficiency comparing to the standard quantum key distribution schemes. Especially, the separate control mode does not need in the proposed scheme so that it is simpler and more available than previous ping-pong schemes. The attacker may be detected easily through the fidelity of the transmitted signal, and may not be successful in the beam splitter attack strategy.

Almost pure TM or TE component far field in vector cosine-Gaussian beams

The vectorial structure of cosine-Gaussian beams (cGBs) is investigated in the far field regime based on the vector plane wave spectrum and the method of stationary phase. The energy flux densities of TE or TM term and the ratio of the energy flux of TE or TM term in the whole beam are demonstrated. It is found that the spot configurations of the energy flux densities associated with the TE and TM terms depend on the polarization angle and the beam parameter of the incident cGB. And the far field may be entirely transverse magnetic or transverse electric under appropriate polarization angle and beam parameter.

激光脉冲系统时域响应的偏离度参数

从理论上定义了基于高斯脉冲成分分析的激光脉冲时域响应的偏离度参数,并且通过实验验证了该定义的有效性。利用高速光电探测系统测量入射和出射的微秒量级激光脉冲的实际能量分布,在3%的容差范围内对能量分布进行高斯脉冲分量拟合,通过对比各独立高斯成分的归一化强度经系统后的理想值与真实值,计算得到偏离度。在该定义下.通过分析各高斯分量的权重演化以及新分量的成因,不仅可以研究光场与系统相互作用的物理机制,而且为系统的优化设计提供帮助。

猪咳嗽声特征参数提取与识别的研究

为了实现对养猪场猪患咳嗽症状疾病的诊断,试验在猪咳嗽声学特性的基础上,对猪干咳声和湿咳声的梅尔倒谱系数和线性预测倒谱系数两种特征参数进行对比,提出了基于梅尔倒谱系数及其一阶差分为特征参数的隐马尔科夫模型对猪两种咳嗽声的识别方案。结果表明:在提取24维梅尔倒谱系数及其一阶差分,4个高斯混合分量描述观测向量输出分布时,建立的隐马尔科夫模型对猪两种咳嗽声的识别率最高。此方案可以有效完成养殖场猪咳嗽声的识别,有助于养猪场自动化监控。

Influence of wave normal angle on gyroresonance between chorus waves and outer radiation belt electrons

In this paper, using a Gaussian distribution of wave normal angle X=tan0, and considering contributions of harmonic resonances n up to ＋5, we analyze the effect of normal angle on diffusion coefficients induced by gyroresonance between chorus waves and electrons with energies 0.1 and 1.0 MeV on the dayside and nightside at L=4.5. When pitch angle a~〉10~, for 0.1 and 1,0 MeV electrons on the dayside and nightside, diffusion coefficients of five orders （-2, -1, 0, 1, 2） decrease with in- creasing normal angle peak, leading to the total diffusion coefficients decreasing with increasing peak. When ae〈10~, for 1.0 MeV electrons on the dayside and 0.1 MeV electrons on the dayside and nightside, the positive order diffusion coefficients are generally smaller than the same negative order ones; in the meanwhile, diffusion coefficients of orders （-2, 1, 2） are very small, the dominant order n=-I diffusion coefficients change very little, hence the total diffusion coefficients almost remain un- changed. However, for 1.0 MeV electrons on the nightside, diffusion coefficients of orders （-2, 1, 2） which are larger than those of the order （-1） resonance increase with increasing peak, hence the total diffusion coefficients increase with increasing peak. The current results show that the wave normal angle plays an important role in the quantitative analysis of gyroresonance between chorus waves and electrons in the outer radiation belt.

Drift perturbation of subordinate Brownian motions with Gaussian component

Let d ≥ 1 and Z be a subordinate Brownian motion on R^d with infinitesimal generator ? + ψ(?),where ψ is the Laplace exponent of a one-dimensional non-decreasing L′evy process(called subordinator). We establish the existence and uniqueness of fundamental solution(also called heat kernel) pb(t, x, y) for non-local operator L^b= ? + ψ(?) + b ?, where Rb is an Rd-valued function in Kato class K_(d,1). We show that p^b(t, x, y)is jointly continuous and derive its sharp two-sided estimates. The kernel pb(t, x, y) determines a conservative Feller process X. We further show that the law of X is the unique solution of the martingale problem for(L^b, C_c~∞(R^d)) and X is a weak solution of Xt = X0+ Zt + integral from n=0 to t(b(Xs)ds, t ≥ 0).Moreover, we prove that the above stochastic differential equation has a unique weak solution.

Fractional Fourier transform of Lorentz-Gauss vortex beams

An analytical expression for a Lorentz-Gauss vortex beam passing through a fractional Fourier transform (FRFT) system is derived. The influences of the order of the FRFT and the topological charge on the normalized intensity distribution, the phase distribution, and the orbital angular momentum density of a Lorentz-Gauss vortex beam in the FRFT plane are examined. The order of the FRFT controls the beam spot size, the orientation of the beam spot, the spiral direction of the phase distribution, the spatial orientation of the two peaks in the orbital angular momentum density distribution, and the magnitude of the orbital angular momentum density. The increase of the topological charge not only results in the dark-hollow region becoming large, but also brings about detail changes in the beam profile. The spatial orientation of the two peaks in the orbital angular momentum density distribution and the phase distribution also depend on the topological charge.

Large Amplitude Dust Ion Acoustic Solitons and Double Layers in Dusty Plasmas with Ion Streaming and High-Energy Tail Electron Distribution

Large amplitude dust ion acoustic （DIA） solitons as well as double layers （DLs） are studied in a dusty plasma having a high-energy-tail electron distribution. The influence of electron deviation from the Maxwellian distribution and ion streaming on the existence domain of solitons is discussed in the （M, f） space using the pseudo-potential approach. It is found that in the presence of streaming ions and for a fixed f, solitons may appear for larger values of M. This means that in the presence of ion streaming, high values of the Mach number are needed to have soliton. The DIA solitary waves profile is highly sensitive to the ion streaming speed. Their amplitude is found to decrease with an increase of the ion streaming speed. In addition, we find that the ion streaming effect may lead to the appearance of double layers. The results of this axticle should be useful in understanding the basic nonlinear features of DIA waves propagating in space dusty plasmas, especially those including a relative motion between species, such as comet tails and solar wind streams, etc.