Acoustic characteristics of children''s voice

Four acoustic measures were taken from voice recordings of 121 children between the ages of 64 and 134 months. Acoustic parameters were measured on a sustained neutral /a/ vowel, produced imitatively at normal pitch and loudness. Samples were analyzed for fundamental frequency, jitter, shimmer, and signal-to-noise ratio (SNR). Data are presented to characterize effects of age, sex, height, and weight on these acoustic parameters. Results indicate statistically significant relationships between frequency and sex, with higher frequencies for girls. Also significant is a positive relationship between shimmer and height and a negative relationship between SNR and height.     

Asymptotic Spectra of Trapping Sets in Regular and Irregular LDPC Code Ensembles

We evaluate the asymptotic normalized average distributions of a class of combinatorial configurations in random, regular and irregular, binary low-density parity-check (LDPC) code ensembles. Among the configurations considered are trapping and stopping sets. These sets represent subsets of variable nodes in the Tanner graph of a code that play an important role in determining the height and point of onset of the error-floor in its performance curve. The techniques used for deriving the spectra include large deviations theory and statistical methods for enumerating binary matrices with prescribed row and column sums. These techniques can also be applied in a setting that involves more general structural entities such as subcodes and/or minimal codewords, that are known to characterize other important properties of soft-decision decoders of linear block codes     

Coding in 2D: Using Intentional Dispersity to Enhance the Information Capacity of Sequence‐Coded Polymer Barcodes

A 2D approach was studied for the design of polymer‐based molecular barcodes. Uniform oligo(alkoxyamine amide)s, containing a monomer‐coded binary message, were synthesized by orthogonal solid‐phase chemistry. Sets of oligomers with different chain‐lengths were prepared. The physical mixture of these uniform oligomers leads to an intentional dispersity (1st dimension fingerprint), which is measured by electrospray mass spectrometry. Furthermore, the monomer sequence of each component of the mass distribution can be analyzed by tandem mass spectrometry (2nd dimension sequencing). By summing the sequence information of all components, a binary message can be read. A 4‐bytes extended ASCII‐coded message was written on a set of six uniform oligomers. Alternatively, a 3‐bytes sequence was written on a set of five oligomers. In both cases, the coded binary information was recovered.     

The third support weight enumerators of the doubly-even, self-dual [32,16,8] codes

We present combinatorial methods for computing the third support weight enumerators of the five doubly-even, self-dual [32,16,8] codes. The methods exploit relationships that exist between support weight enumerators and complete coset weight enumerators of a self-dual code.     

Shortened Array Codes of Large Girth

One approach to designing structured low-density parity-check (LDPC) codes with large girth is to shorten codes with small girth in such a manner that the deleted columns of the parity-check matrix contain all the variables involved in short cycles. This approach is especially effective if the parity-check matrix of a code is a matrix composed of blocks of circulant permutation matrices, as is the case for the class of codes known as array codes. We show how to shorten array codes by deleting certain columns of their parity-check matrices so as to increase their girth. The shortening approach is based on the observation that for array codes, and in fact for a slightly more general class of LDPC codes, the cycles in the corresponding Tanner graph are governed by certain homogeneous linear equations with integer coefficients. Consequently, we can selectively eliminate cycles from an array code by only retaining those columns from the parity-check matrix of the original code that are indexed by integer sequences that do not contain solutions to the equations governing those cycles. We provide Ramsey-theoretic estimates for the maximum number of columns that can be retained from the original parity-check matrix with the property that the sequence of their indices avoid solutions to various types of cycle-governing equations. This translates to estimates of the rate penalty incurred in shortening a code to eliminate cycles. Simulation results show that for the codes considered, shortening them to increase the girth can lead to significant gains in signal-to-noise ratio (SNR) in the case of communication over an additive white Gaussian noise (AWGN) channel     

Subspace Pursuit for Compressive Sensing Signal Reconstruction

We propose a new method for reconstruction of sparse signals with and without noisy perturbations, termed the subspace pursuit algorithm. The algorithm has two important characteristics: low computational complexity, comparable to that of orthogonal matching pursuit techniques when applied to very sparse signals, and reconstruction accuracy of the same order as that of linear programming (LP) optimization methods. The presented analysis shows that in the noiseless setting, the proposed algorithm can exactly reconstruct arbitrary sparse signals provided that the sensing matrix satisfies the restricted isometry property with a constant parameter. In the noisy setting and in the case that the signal is not exactly sparse, it can be shown that the mean-squared error of the reconstruction is upper-bounded by constant multiples of the measurement and signal perturbation energies.     

Determination of microamounts of zirconium(IV) and titanium(IV) with preliminary TLC separation

By the application of thin-layer chromatography on silica gel H and the solvent system consisting of 6 M HCl:acetylacetone: 9 M H₂SO₄ (60:2:1, v/v/v), zirconium and titanium have been quantitatively separated from each other, as well as from numerous other interfering ions. The efficiency of the chromatographic separation was evaluated by semiquantitative determination of zirconium and titanium by visual colorimetry of spots in situ, as well as by spectrophotometric determination of zirconium with rutin after its elution from silica gel H thin-layer.     

Rotational polygon overlap minimization and compaction

An effective and fast algorithm is given for rotational overlap minimization: given an overlapping layout of polygons P₁, P₂, P₃, …, P_k in a container polygon Q, translate and rotate the polygons to diminish their overlap to a local minimum. A (local) overlap minimum has the property that any perturbation of the polygons increases the overlap. Overlap minimization is modified to create a practical algorithm for compaction: starting with a non-overlapping layout in a rectangular container, plan a non-overlapping motion that diminishes the length or area of the container to a local minimum. Experiments show that both overlap minimization and compaction work well in practice and are likely to be useful in industrial applications.     

Scrambling for nonequiprobable signalling

A scrambling method for nonequiprobable signalling is proposed. This method uses a lossless compression decoder to produce symbols with unequal probabilities. The relative symbol frequencies and correlation characteristics are calculated and the noisy channel error performance is discussed. In one application of this nonequiprobable signalling procedure it is shown that 0.68 dB of a possible 1.53 dB gain is easily obtained for signal constellation shaping applications