We introduce the notion of a duality pair and demonstrate how the left half of such a pair is “often” covering and preenveloping. As an application, we generalize a result by Enochs et al. on Auslander and Bass classes, and we prove that the class of Gorenstein injective modules—introduced by Enochs and Jenda—is covering when the ground ring has a dualizing complex.

A pair of sequences (αn(a, k, q),βn(a, k, q)) such that α0(a, k, q) = 1 and βn(a, k, q) = n ∑ j=0 (k/a; q)n−j(k; q)n+j (q; q)n−j(aq; q)n+j αj(a, k, q) is termed a WP-Bailey Pair. Upon setting k = 0 in such a pair we obtain a Bailey pair. In the present paper we consider the problem of “lifting” a Bailey pair to a WPBailey pair, and use some of the new WP-Bailey pairs found in this way to derive...

With considering a ‘triangle of three major currency pairs’, there is a tiny difference between multiplication of exchange rate for the first two currency pairs and the third. To discover whether this little difference can lead to a neutral arbitrage or not, I took portfolios of 35 baskets of three major currency pairs(combinations of all 7 major currencies). There are eight approaches (differe...

The topological indices, defined as the sum of contributions of all pairs of vertices (among which are the Wiener, Harary, hyper–Wiener indices, degree distance, and many others), are expressed in terms of contributions of edges and pairs of edges.

In this paper, an efficient transcoding algorithm between G.723.1 and AMR speech coders is proposed for providing interoperability between IP and mobile networks. Transcoding is completed through three processing steps: line spectral pair (LSP) conversion, pitch interval conversion, and fast adaptivecodebook search. For maintaining minimum distortion, sensitive parameters to quality such as ada...

An artificial neural network (ANN) based helicopter identification system is proposed. The feature vectors are based on both the tonal and the broadband spectrum of the helicopter signal. ANN pattern classifiers are trained using various parametric spectral representation techniques. Specifically, linear prediction, reflection coefficients, cepstrum, and line spectral frequencies (LSF) are comp...

Oneafthemorecomputationally intensivepwtionsofspeechcoding algorithms using linear predictive (LP) m e t h d is the calculation of line specual frequencies (LSFs) from the predictor ccefficients. Methods for the efficient mmpuration of LSFs have been dereloped. A very large scale integration ("LSI) design implementing one such method is presented. The architecture is designed to be optimized fo...

This paper presents a method to model the global variance (GV) of log power spectrums derived from the line spectral pairs (LSPs) in a sentence for HMM-based parametric speech synthesis. Different from the conventional GV method where the observations for GV model training are the variances of spectral parameters for each training sentence, our proposed method directly models the temporal varia...