Decomposition of Binary Matrices and Fast Hadamard Transforms

Binary matrices or (± 1)-matrices have numerous applications in coding, signal processing, and communications. In this paper, a general and efficient algorithm for decomposition of binary matrices and the corresponding fast transform is developed. As a special case, Hadamard matrices are considered. The difficulties of the construction of 4n-point Hadamard transforms are related to the Hadamard problem: the question of the existence of Hadamard matrices. (It is not known whether for every integer n, there is an orthogonal 4n × 4n matrix with elements ± 1.) In the derived fast algorithms, the number of real operations is reduced from O(N²) to O(N log N) compared to direct computation. The proposed scheme requires no zero padding of the input data. Comparisions revealing the efficiency of the proposed algorithms with respect to the known ones are given. In particular, it is demonstrated that, in typical applications, the proposed algorithm is significantly more efficient than the conventional Walsh-Hadamard transform. Note that for Hadamard matrices of orders ≥ 96 the general algorithm is more efficient than the classical Walsh-Hadamard transform whose order is a power of 2. The algorithm has a simple and symmetric structure. The results of numerical examples are presented.     

The computational power of cell division in P systems: Beating down parallel computers?

We study the computational power of cell division operations in the formalframework of P systems, a mathematical model of cell-like membrane structure with regulated transport of objects (molecules) through membranes. We show that a uniformfamily of P systems with active membranes and2-division is able to solve the well-known PSPACE-complete problem QBF inlinear time. This result implies that such a family of P systems modelling celldivision is at least as powerful as so-called Second Machine Class computers. The Second Machine Class, containing most of the fundamental parallelcomputer models such as parallel RAM machines of types SIMD and MIMD, vector machinesand others, is characterized by using an exponential amount of resources(processing units) with respect to the computing time.     

Performance of a wireless MC-CDMA system with an antenna array in afading channel: reverse link

We propose a multicarrier code-division multiple-access (MC-CDMA) system employing an antenna array at the base station, and analyze the performance of the MC-CDMA system in a fading channel. An optimal beamformer not requiring explicit direction of arrival estimation or training signals is derived for the MC-CDMA system in the reverse link, and is shown to reduce interferences from other users significantly, thus increasing the system's user capacity. Also, it is shown that the MC-CDMA approach can achieve better performance than the direct-sequence CDMA approach when both approaches employ the code filtering technique for the antenna array     

An adaptive text-line extraction algorithm for printed Arabic documents with diacritics

Multimedia Tools and Applications - The performance of document text recognition depends on text line segmentation algorithms, which heavily relies on the type of language, author’s writing...     

Transform-based image enhancement algorithms with performancemeasure

This paper presents a new class of the "frequency domain"-based signal/image enhancement algorithms including magnitude reduction, log-magnitude reduction, iterative magnitude and a log-reduction zonal magnitude technique. These algorithms are described and applied for detection and visualization of objects within an image. The new technique is based on the so-called sequency ordered orthogonal transforms, which include the well-known Fourier, Hartley, cosine, and Hadamard transforms, as well as new enhancement parametric operators. A wide range of image characteristics can be obtained from a single transform, by varying the parameters of the operators. We also introduce a quantifying method to measure signal/image enhancement called EME. This helps choose the best parameters and transform for each enhancement. A number of experimental results are presented to illustrate the performance of the proposed algorithms.     

Directed evolution of biocircuits using conjugative plasmids and CRISPR-Cas9: design and in silico experiments

Recent links between computer science and synthetic biology allow for construction of many kinds of algorithmic processes within cells, obtained either by a direct engineered design or by an evolutionary search. In the latter case, horizontal gene transfer and especially transfer of plasmids by conjugation is generally respected as a crucial source of genetic diversity in bacteria. While some previous studies focused on mutations as the crucial principle to obtain diversity for engineered evolution, here we consider conjugation itself as a tool to generate diversity from a pre-determined library of biocircuits basic components. The recent development of CRISPR-Cas9 and its programmable DNA cutting ability makes it a powerful selection tool able to remove nonfunctional biocircuits from a cell population. In this paper, we describe a framework for controlled bacterial evolution of biocircuits based on conjugation and on CRISPR-Cas9, resulting in a direct biological implementation of an evolutionary algorithm. In silico experiments provide data to estimate the computational/search capability of plasmid-based engineered evolution.