FREQUENCY ANALYSIS OF RLE-BLOCKS REPETITIONS IN THE SERIES OF BINARY CODES WITH OPTIMAL MINIMAX CRITERION OF AUTOCORRELATION FUNCTION

The article describes the problem of searching for binary pseudo-random sequences with quasi-ideal autocorrelation function, which are to be used in contemporary communication systems, including mobile and wireless data transfer interfaces. In the synthesis of binary sequences sets, the target set is manning them based on the minimax criterion by which a sequence is considered to be optimal according to the intended application. In the course of the research the optimal sequences with order of up to 52 were obtained; the analysis of Run Length Encoding was carried out. The analysis showed regularities in the distribution of series number of different lengths in the codes that are optimal on the chosen criteria, which would make it possible to optimize the searching process for such codes in the future

Parallel search for signals with specified cross- and autocorrelation properties on multiprocessor platforms

The article introduces the program application for seeking binary signals of specified bit length that have specified correlative properties. The application seeks these codes using parallel (multithreaded) permutation of the possible values from all of the range specified by a bit length. The article contains the results of researches of speed parameters of the permutator working in single–threaded and multithreaded modes. Analysis was made for multithreaded specific conditions of speed reductions. The researches are made according to the priority national project "Education" in the centre of high performance computations of the Far Eastern National Technical University. The centre allows parallel computations in remote access

Novel Antireflection Coatings Obtained by Low-Temperature Annealing in the Presence of Tetrabutylammonium Bromide and Gold Nanoparticles

In this work, nanoporous antireflective coatings on silicate glass were obtained from silicon dioxide sol compositions by the sol-gel method in the presence of quaternary ammonium salt (tetrabutylammonium bromide) at different annealing temperatures (200–250 °C). Varying the salt concentration from 3 to 5 wt.%, we achieved the transmittance of the coatings of about 97% at 250 °C in comparison with 91% for clean glass in the wavelength range from 400 to 1100 nm. The addition of gold nanoparticles to the composition containing 5 wt.% tetrabutylammonium bromide allowed us to decrease the annealing temperature to 200 °C, preserving the transmittance at the level of 96.5%. For this case, the optimal concentration of gold nanoparticles is determined (2.6 × 10−9 mol/mL). According to the SEM analysis, the obtained antireflective coatings contain pores with a minimum area size up to 4 nm2

Porogen Concentration Effect on the Pore Structure and Properties Evolution of Polymer Monolith Based on Oligocarbonate Dimethacrylate OCM-2

Porous polymer monolith materials of 2-mm thickness were obtained by visible light-induced radical polymerization of oligocarbonate dimethacrylate (OCM-2) in the presence of 1-butanol (10 to 70 wt %) as a porogenic additive. The pore characteristics and morphology of polymers were studied by mercury intrusion porosimetry and scanning electron microscopy. Monolithic polymers with both open and closed pores up to 100 nm in size are formed when the alcohol content in the initial composition is up to 20 wt %. The pore structure in such materials is a system of holes in the bulk of the polymer (hole-type pores). Open interconnected pores with a specific volume up to 2.22 cm3/g and modal pore size up to 10 microns are formed in the volume of the polymer with 1-butanol content of more than 30 wt %. Such porous monoliths are a structure of covalently bonded polymer globules (interparticle-type pores). The free space between the globules represents a system of open interconnected pores. In the transition region of 1-butanol concentrations (from 20 to 30 wt %), areas with both structures and intermediate frameworks, as well as honeycomb structures of polymer globules connected by bridges, are fixed on the polymer surface. It was found that the transition from one type of pore system to another is accompanied by a sharp change in the strength characteristics of the polymer. Approximation of experimental data using the sigmoid function made it possible to determine the concentration of the porogenic agent in the vicinity of which the percolation threshold is observed