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共有20条相似文献,以下是第1-20项 搜索用时 85 毫秒

1.  Narrowband speech wideband extension algorithm research  
   ZHANG Yong  LIU Yi《Chinese Journal of Acoustics》,2014年第2期
   To reduce the spectral distortion,a Hidden Markov Model-based narrowband speech bandwidth extension algorithm is presented.Firstly,the parameters which have higher mutual information with wideband envelope were extracted to constitute the feature vector,and then a posterior probability was calculated via the joint probability of the partial observation feature vector sequence and the markov states.Secondly,based on the posterior probability,the wideband envelope was estimated using Bayesian parameter estimation method and minimum mean square error criteria.For estimation of wideband excitation signal,intermediate frequency extension algorithm is proposed based on the harmonic correlation between the low frequency and high frequency.The experimental results show that,compared with the traditional bandwidth extension algorithm based on Hidden Markov Model,the average spectral distortion is reduced by 0.187 dB and the number of speech frame with spectral distortion over10dB is decreased by 34.3%.    

2.  基于一阶Takagi-Sugeno系统的Pi-Sigma网络的改进神经-模糊梯度学习算法  
   刘燕  杨洁  杨达坤  吴微《数学研究及应用》,2014年第34卷第1期
   This paper presents a Pi-Sigma network to identify first-order Tagaki-Sugeno(T-S) fuzzy inference system and proposes a simplified gradient-based neuro-fuzzy learning algorithm.A comprehensive study on the weak and strong convergence for the learning method is made,which indicates that the sequence of error function goes to a fixed value,and the gradient of the error function goes to zero,respectively.    

3.  Error Thresholds in Single-Peak Gaussian Distributed Fitness Landscapes  
   FENG Xiao-Li GU Jian-Zhong LI Yu-Xiao ZHUO Yi-Zhong《理论物理通讯》,2007年第48卷第4期
   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.    

4.  Weakly Sequential Completeness of Orlicz Spaces  
   王玉文《数学研究与评论》,1986年第1期
   Banach space X is called to be weakly sequential complete space, if foreach weak Cauchy Sequence {x_n} in X, there exists a element in X such that x_n→x (n→∞). Weakly sequential completeness in close relationship with refrexivity、separability、weak convexity、bases and isomorphic subspaces in Banach spaces.    

5.  Approximation of weak sense stationary stochastic processes from local averages  被引次数:2
   Zhan-jie SONG  Wen-chang SUN  Shou-yuan YANG & Guang-wen ZHU School of Science  Tianjin University  Tianjin 300072  China   Department of Mathematics and LPMC  Nankai University  Tianjin 300071  China   National Ocean Technology Center  Tianjin 300111  China《中国科学A辑(英文版)》,2007年第50卷第4期
   We show that a weak sense stationary stochastic process can be approximated by local averages. Explicit error bounds are given. Our result improves an early one from Splettstosser.    

6.  HERMITE-FEJER-TYPE OPERATORS Ⅰ  
   《分析论及其应用》,1994年第4期
   The aun of this paper is to investigate Hermite-Fejer-type interpolation operators based on the zeros ofJacobi polynomails.To achieve our goal,we develop a new technique for deriving error estimates for these op-erators.    

7.  Oscillation Theorems of the Second Order Linear Matrix Differential System with Damping  
   QiGuiYANG《数学学报(英文版)》,2005年第21卷第1期
   By using the Riccati technique and the technique, new oscillation criteria are obtained for the second order matrix differential system(P(t)Y′(t))′ r(t)P(t)Y′(t) Q(t)Y(t) = 0, t≥t0.These results in the present paper generalize and improve many known conclusions. Furthermore, some results are different from the most known ones in the sense that they are based on the information only on a sequence of subintervals of [t0, ∞), rather than on the whole half-line. In particular, our results complement a number of existing results and handle the ease that is not covered by the known criteria.    

8.  Chaos game representation (CGR)-walk model for DNA sequences  被引次数:1
   高洁  徐振源《中国物理 B》,2009年第18卷第1期
   Chaos game representation(CGR) is an iterative mapping technique that processes sequences of units,such as nucleotides in a DNA sequence or amino acids in a protein,in order to determine the coordinates of their positions in a continuous space.This distribution of positions has two features:one is unique,and the other is source sequence that can be recovered from the coordinates so that the distance between positions may serve as a measure of similarity between the corresponding sequences.A CGR-walk model is proposed based on CGR coordinates for the DNA sequences.The CGR coordinates are converted into a time series,and a long-memory ARFIMA(p,d,q) model,where ARFIMA stands for autoregressive fractionally integrated moving average,is introduced into the DNA sequence analysis.This model is applied to simulating real CGR-walk sequence data of ten genomic sequences.Remarkably long-range correlations are uncovered in the data,and the results from these models are reasonably fitted with those from the ARFIMA(p,d,q) model.    

9.  二阶非线性矩阵微分方程的振动性  
   徐衍聪  孟凡伟《高校应用数学学报(英文版)》,2006年第21卷第3期
   Some new oscillation criteria are established for the second-order matrix differential system(r(t)Z′(t))′ p(t)Z′(t) Q(t)F(Z′(t))G(Z(t)) = 0, t ≥ to > 0,are different from most known ones in the sense that they are based on the information only on a sequence of subintervals of [t0, ∞), rather than on the whole half-line. The results weaken the condition of Q(t) and generalize some well-known results of Wong (1999) to nonlinear matrix differential equation.    

10.  Rademacher complexity in Neyman-Pearson classification  
   Min Han  Di Rong Chen  Zhao Xu Sun《数学学报(英文版)》,2009年第25卷第5期
   Neyman-Pearson(NP) criterion is one of the most important ways in hypothesis testing. It is also a criterion for classification. This paper addresses the problem of bounding the estimation error of NP classification, in terms of Rademacher averages. We investigate the behavior of the global and local Rademacher averages, and present new NP classification error bounds which are based on the localized averages, and indicate how the estimation error can be estimated without a priori knowledge of the class at hand.    

11.  Weak and Strong Convergence for Fixed Points of Asymptotically Non-expansive Mappings  
   ZeQingLIU ShinMinKANG《数学学报(英文版)》,2004年第20卷第6期
   A few weak and strong convergence theorems of the modified three-step iterative sequence with errors and the modified Ishikawa iterative sequence with errors for asymptotically non-expansive mappings in any non-empty closed convex subsets of uniformly convex Banach spaces are established. The results presented in this paper substantially extend the results due to Chang (2001), Osilike and hniagbosor (2000), Rhoades (1994) and Schu (1991).    

12.  闭序列覆盖映射的一些注记  
   林福财  林寿《数学研究及应用》,2014年第34卷第1期
   In this paper, we mainly discuss the images of certain spaces under closed sequencecovering maps. It is showed that the property with a locally countable weak base is preserved by closed sequence-covering maps. And the following question is discussed: Are the closed sequence-covering images of spaces with a point-countable sn-network sn-first countable?    

13.  The precise asymptotics of the complete convergence for moving average processes of <Emphasis Type="Italic">m</Emphasis>-dependent <Emphasis Type="Italic">B</Emphasis>-valued elements  
   Xi Li Tan  Xiao Yun Yang《数学学报(英文版)》,2009年第25卷第3期
   Let {εt;t ∈ Z} be a sequence of m-dependent B-valued random elements with mean zeros and finite second moment. {a3;j ∈ Z} is a sequence of real numbers satisfying ∑j=-∞^∞|aj| 〈 ∞. Define a moving average process Xt = ∑j=-∞^∞aj+tEj,t ≥ 1, and Sn = ∑t=1^n Xt,n ≥ 1. In this article, by using the weak convergence theorem of { Sn/√ n _〉 1}, we study the precise asymptotics of the complete convergence for the sequence {Xt; t ∈ N}.    

14.  LOCALLY STABILIZED FINITE ELEMENT METHOD FOR STOKES PROBLEM WITH NONLINEAR SLIP BOUNDARY CONDITIONS  
   Yuan Li  Kai-tai Li《计算数学(英文版)》,2010年第6期
   Based on the low-order conforming finite element subspace (Vh, Mh) such as the P1-P0 triangle element or the Q1-P0 quadrilateral element, the locally stabilized finite element method for the Stokes problem with nonlinear slip boundary conditions is investigated in this paper. For this class of nonlinear slip boundary conditions including the subdifferential property, the weak variational formulation associated with the Stokes problem is an variational inequality. Since (Vh, Mh) does not satisfy the discrete inf-sup conditions, a macroelement condition is introduced for constructing the locally stabilized formulation such that the stability of (Vh, Mh) is established. Under these conditions, we obtain the H1 and L2 error estimates for the numerical solutions.    

15.  二次变系数椭圆方程的三次有限体积元方法  
   杨旻《东北数学》,2005年第2期
   In this paper, we present a finite volume framework for second order elliptic equations with variable coefficients based on cubic Hermite element. We prove the optimal H1 norm error estimates. A numerical example is given at the end to show the feasibility of the method.    

16.  A note on self-normalized Dickey-Fuller test for unit root in autoregressive time series with GARCH errors  
   Xiao-rong Yang  Li-xin Zhang《高校应用数学学报(英文版)》,2008年第23卷第2期
   In this article, the unit root test for AR(p) model with GARCH errors is considered. The Dickey-Fuller test statistics are rewritten in the form of self-normalized sums, and the asymptotic distribution of the test statistics is derived under the weak conditions.    

17.  A Secure communication method for a high-power information signal based on chaotic masking  被引次数:3
   李建芬  李农《中国物理》,2002年第11卷第11期
   In this paper,we present a secure communication method for a high-power information signal based on chaotic masking.In the transmitter,an adaptive controller is adopted to pick up the change of the information signal ,and to inject the controller‘s error into the transmitting system.At the same time,the information is directly added to the chaotic signal in transmission to drive the receiving system.In the receiver,another adaptive controller is used to maintain chaotic synchronization of the transmitting and receiving systems and to recover the information signal.Since the synchronization error is independent from the information signal,the power of the information signal can be equivalent to that of the chaotic signal,and the frequency of the information signal can be set within the range of the principal frequencies of the chaotic signal,The results of theoretical analysis and numerical simulation show that the presented method not only enhances the degree of security of low-dimensional chaotic systems but also significantly improves the signal-to-noise ratio at the receiving end.    

18.  Convergence of gradient method for Elman networks  
   吴微  徐东坡  李正学《应用数学和力学(英文版)》,2008年第29卷第9期
   The gradient method for training Elman networks with a finite training sample set is considered. Monotonicity of the error function in the iteration is shown. Weak and strong convergence results are proved, indicating that the gradient of the error function goes to zero and the weight sequence goes to a fixed point, respectively. A numerical example is given to support the theoretical findings.    

19.  Average widths of anisotropic Besov-Wiener classes  
   JIANG Yanjie《中国科学A辑(英文版)》,2000年第43卷第6期
   This paper concerns the problem of average σ-K width and average σ-L width of some anisotropic Besov-Wiener classes Srp q θb(Rd) and Srp q θB(Rd) in Lq(Rd) (1≤q≤p<∞). The weak asymptotic behavior is established for the corresponding quantities.    

20.  THE AVERAGE CASE COMPLEXITY OF THE SHIFT-INVARIANT PROBLEM  被引次数:1
   Arthur.G.Werschulz《分析论及其应用》,1998年第14卷第1期
   The present paper deals with the average case, complexity of the shift-invariant problem. The main aim is to give a new proof of the upper bound of average error of finite element method. Our method is based on the techniques proposed by Heinrich(1990). We also point out an essential error regarding the proof of the upper bound in A. G. Werschulz(1991).    

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