18219094
Nonuniform sequential sampling for signal analysis
New electronic technologies for signal analysis raise the possibility of sampling very rapidly, with a time-varying density, and determining empirically both the sampling rate and the window width as the signal evolves in time. These opportunities also point to the possibility of sequentially sampling in a time-varying way in more traditional problems. Motivated by these ideas, we establish a sampling formula, valid in cases where both sampling rate and window width may be varied. The formula states that, in terms of the ways in which these quantities should alter with time, optimal performance is achieved when the window width is inversely proportional to squared sampling rate, and sampling rate is directly proportional to squared bias.
17275266
On Gauss quadrature and partial cross validation
New estimators of expected values Ew(X) of functions of a random variable X are introduced. The new estimators are based on Gauss quadrature, a numerical method frequently used to approximate integrals over finite intervals. The estimators need a small number of numerical evaluations and hence are useful in partial cross validation (PCV) a numerical method for finding optimal smoothing parameters in nonparametric curve estimation. The PCV can considerably reduce the computational cost of the generalized cross validation method typically used to determine the optimal smoothing parameter.
5254546
Constructions for Perfect 5-Deletion-Correcting Codes of Length$7$
There are two kinds of perfect (k-t)-deletion-correcting codes with words of length k over an alphabet of size v, those where the coordinates may be equal and those where all coordinates must be different. We call these two kinds of codes T*(t,k,v)-codes and T(t,k,v)-codes respectively. Both a T*(t,k,v)-code and a T(t,k,v)-code are capable of correcting any combination of up to (k-t) deletions and insertions of letters occurred in transmission of codewords. In this correspondence, we consider constructions for the codes from directed designs. By means of these constructions, the existence of a T(2,7,v)-code is settled for all positive integers v with the exception of 68 values of v; T*(2,7,v)-codes are constructed for all integers vges2350. A large number of explicit constructions for T*(2,7,v)-codes with v<2350 are also presented
16485753
An integrated approach to robust speaker identification and speech recognition
Conventional speaker identification and speech recognition algorithms cannot deal with noisy and multiple speaker environments. For example, IBM via Voice has low recognition rates if dictation is done in a noisy environment. In order to achieve high performance in speaker identification and speech recognition, we propose an integrated approach that takes every facet of the process into account. Here we summarize some preliminary results from the application of this integrated approach to robust speaker identification and speech recognition. A real-time stand-alone software prototype has been developed to evaluate the effectiveness of the approach.
29194002
On the existence of perfect Mendelsohn designs with k = 7 and lambda even
Abstract Let v, k and λ be positive integers. A ( v, k , λ)- Mendelsohn design (briefly ( v, k , λ)-MD) is a pair ( X ,B) where X is a v -set (of points ) andBis a collection of cyclically ordered k -subsets of X (called blocks ) such that every ordered pair of points of X are consecutive in exactly λ blocks of B. A set of k distinct elements { a 1 , a 2 , ..., a k } is said to be cyclically ordered by a 1 a 2 a k a 1 and the pair a i , a i + t are said to be t -part in a cyclic k -tuple ( a 1 , a 2 ,..., a k ) where i + t is taken modulo k . If for all t = 1, 2,..., k − 1, every ordered pair of points of X are t -apart in exactly λ blocks of B, then the ( v, k , λ)-MD is called perfect and is denoted briefly by ( v, k , λ)-PMD. A necessary condition for the existence of a ( v, k , λ)-PMD is λ v ( v −1)≡0 (mod k ). In this paper, we shall be concerned mostly with the case k = 7 and λ even. It will be shown that the necessary condition for the existence of a v , 7, λ)-PMD, namely λ v ( v −1)≡0 (mod 7), is also sufficient for all even λ ⪖ 16, with at most 29 possible exceptions for the pair ( v , λ) where λ is even and λ v ≡0 or 1 (mod 7) for the existence of a ( v , 7, 1)-PMD is also sufficient for all v ⪖ 421 with at most 40 possible exceptions below this value, which improves the earlier results.
7184753
Speech separation algorithms for multiple speaker environments
Conventional speaker identification and speech recognition algorithms do not perform well if there are multiple speakers in the background. For high performance speaker identification and speech recognition applications in multiple speaker environments, a speech separation stage is essential. Here we summarize the implementation of three speech separation techniques. Advantages and disadvantages of each method are highlighted, as no single method can work under all situations. Stand-alone software prototypes for these methods have been developed and evaluated.
18873920
Signal Sets From Functions With Optimum Nonlinearity
Signal sets with the best correlation property are desirable in code-division multiple-access (CDMA) systems. In this paper, the construction of Wootters and Fields for mutually unbiased bases is extended into a generic construction of signal sets using planar functions. Then, specific classes of planar functions and almost bent functions are employed to obtain (q2+q,q) signal sets. The signal sets derived from planar functions are optimal with respect to the Levenstein bound, and those obtained from almost bent functions nearly meet the Levenstein bound. The signal sets constructed in this paper could have a very small alphabet size, and have applications in synchronous DS-CDMA systems, where the number of users is greater than the signal space dimension or the spreading factor