Fixed-point realization of fast nonlinear Fourier transform algorithm for FPGA implementation of optical data processing

The nonlinear Fourier transform (NFT) based signal processing has attracted considerable attention as a promising tool for fibre nonlinearity mitigation in optical transmission. However, the mathematical complexity of NFT algorithms and the noticeable distinction of the latter from the “conventional” (Fourier-based) methods make it difficult to adapt this approach for practical applications. In our work, we demonstrate a hardware implementation of the fast direct NFT operation: it is used to map the optical signal onto its nonlinear Fourier spectrum, i.e. to demodulate the data. The main component of the algorithm is the matrix-multiplier unit, implemented on field-programmable gate arrays (FPGA) and used in our study for the estimation of required hardware resources. To design the best performing implementation in limited resources, we carry out the processing accuracy analysis to estimate the optimal bit width. The fast NFT algorithm that we analyse, is based on the FFT, which leads to the O(N log^{2}_{2} N) method’s complexity for the signal consisting of N samples. Our analysis revealed the significant demand in DSP blocks on the used board, which is caused by the complex-valued matrix operations and FFTs. Nevertheless, it seems to be possible to utilise further the parallelisation of our NFT-processing implementation for the more efficient NFT hardware realisation

Polyhedrons over Finite Abelian Groups and Their Cryptographic Applications

We are using the group-theory methods for justification of algebraic method in cryptanalysis. The obtained results are using for investigation of Boolean functions cryptographic properties

СЕРВІС ДЛЯ ВІДДАЛЕНИХ ТЕЛЕМЕДИЧНИХ КОНСУЛЬТАЦІЙ ІЗ ВИКОРИСТАННЯМ ВІРТУАЛЬНИХ МАШИН У ГРІД

Для вирішення сучасних ресурсоємних завдань у різних галузях науки та техніки академічний ГРІД-сегмент було розвинуто до національного рівня (УНГ). Він увійшов до світових ГРІД-інфраструктур, наприклад EGI, та широко застосовується в прикладних проектах у різних галузях. Так, для завдань медичних популяційних досліджень неінфекційних захворювань з вико ристанням ГРІД-інфраструктури в Україні було створено проект MedGrid. У рамках даного проекту вже проведено роботи щодо накопичення електрокардіограм у форматі SCP на сховищах даних УНГ з реплікацією та проведення масових досліджень накопичених даних. У результаті співпраці з лікарями провідних закладів охорони здоров'я виявилося, що актуальними є завдання проведення аналізу та візуалізації окремих медичних досліджень із можливістю надання віддалених телемедичних консультацій

Perfectly Balanced Functions in Symbolic Dynamics

In the present paper we study properties of perfectly balanced Boolean functions. Based on the concept of Boolean function barrier, we propose a novel approach to construct large classes of perfectly balanced Boolean functions

ІНТЕГРОВАНЕ СЕРЕДОВИЩЕ ВІРТУАЛЬНОЇ ЛАБОРАТОРІЇ MolDynGrid ДЛЯ РОЗРАХУНКІВ МОЛЕКУЛЯРНОЇ ДИНАМІКИ БІОПОЛІМЕРІВ

Virtual laboratory MolDynGrid has been established in the frame of the Ukrainian academic grid infrastructure for the calculations of molecular dynamics of biological macromolecules.The integrated environment is introduced in virtual laboratory MolDynGrid for the automation of computational  calculations. А web-portal of virtual laboratory has been created (http://moldyngrid.org), which is composed of  computational, analytical and educational blocks аnd data base of molecular dynamics simulations.Виртуальная лаборатория MolDynGrid создана в рамках украинской академической грид-инфраструктуры  для проведения расчетов молекулярной динамики биологических макромолекул. В  виртуальной лаборатории MolDynGrid внедрена интегрированная среда для автоматизации компьютерных расчетов. Создан веб-портал виртуальной лаборатории (http://moldyngrid.org), который состоит из расчетного, аналитического и обучающего  блоков и базы данных траекторий молекулярной динамики.Віртуальна лабораторія MolDynGrid створена в рамках української академічної грід-інфраструктури  для проведення розрахунків молекулярної динаміки біологічних макромолекул. В  віртуальній лабораторії MolDynGrid впроваджене інтегроване середовище для автоматизації комп’ютерних розрахунків. Створено веб-портал віртуальної лабораторії, що складається з розрахункового, аналітичного і навчального блоків та бази даних траєкторій молекулярної динаміки

Development of a Technique and Investigation of Capacitance Characteristics of Electrode Materials for Supercapacitors Based on Nitrogen-Doped Carbon Nanotubes

Carbon nanotubes are widely employed as catalyst supports and electrode materials. In our earlier studies, capacitance characteristics of carbon nanotubes (CNTs) and nitrogen-doped carbon nanotubes (N-CNTs) were measured. Voltammetric curves obtained for nitrogen-doped nanotubes in an acid electrolyte showed pseudocapacitance peaks that were caused by electrochemical processes involving nitrogen-containing functional groups. In this study, measurements were made in a two-electrode cell of a supercapacitor with a hydrophilic polypropylene PORP-A1 film serving as a separator in alkaline (6 M KOH solution) and acid (1 M H2SO4 solution) electrolytes using a PARSTAT 4000 potentiostat/galvanostat. A technique was developed to estimate the contribution of electrical double layer (EDL) by subtracting pseudocapacitance from total capacitance of a cell using the Origin 9 software. The contribution of EDL and pseudocapacitance to the capacitance of supercapacitor cells was estimated. The highest capacitance of an electrode material equal to 97.2 F/g (including the EDL capacitance of 65 F/g) was reached for nanotubes doped with 8.5% of nitrogen in an acid electrolyte at a potential scanning rate of 10 mV/s

Structure and properties of aqueous dispersions of sodium dodecyl sulfate with carbon nanotubes

© 2016, Springer Science+Business Media New York.The dispersing action of the surfactant (sodium dodecyl sulfate, SDS) on the carbon nanotubes (CNT) in aqueous medium has been studied. Electron microscopy, molecular docking, NMR and IR spectroscopies were applied to determine the physical-chemical properties of CNT dispersions in SDS—water solutions. It was established that micellar adsorption of the surfactant on the surface of carbon material and solubilization of SDS in aqueous medium contribute to improving CNT dispersing in water solutions. It was shown that the non-polar hydrocarbon radicals of a single surfactant molecule form the highest possible number of contacts with the graphene surface. Upon increase of the SDS in solution these radicals form micelles connected with the surface of the nanotubes. At the sufficiently high SDS concentration the nanotube surface becomes covered with an adsorbed layer of surfactant micelles. Water molecules and sodium cations are concentrated in spaces between micelles. The observed pattern of micellar adsorption is somewhat similar to a loose bilayer of surfactant molecules

Influence of Nature of Functional Groups on Interaction of Tetrasubstituted at Lower Rim p-tert-Butyl Thiacalix[4]arenes in 1,3-Alternate Configuration with Model Lipid Membranes

The influence of p-tert-butyl thiacalix[4]arenes (1,3-alternate) functionalized by N-propyl morpholine, N,N-dipropyliden-amine and aminodiacetate fragments on dynamic structure of liposomal membranes prepared from dipalmitoyl phosphatidylcholine was investigated by means of electron spin resonance spin-probe technique and Fourier transform infrared spectroscopy. Nuclear magnetic resonance and transmission electron microscopy techniques were applied to characterize the interacting systems. The obtained results have shown that all studied calixarenes interact with polar domains of bilayer. Depending on functional groups and hydrophobic/hydrophilic properties of calixarenes they can dip into bilayer, locate close to the surface of bilayer or form bridges between positively charged groups of adjacent lipid molecules, thus assisting to disordering or putting in order the lipid molecules. © 2011 Springer-Verlag

New Gas-Phase Catalytic Oxidative Processes for Desulfurization of Diesel Fuel

An effective gas-phase oxidative desulfurization (ODS) process was proposed. The process was studied in a laboratory reactor with a proprietary catalyst at 300-400 ºС and ambient pressure with model fuels represented by thiophene, dibenzothiophene(DBT) and 4,6-dimethyldibenzothiophene (DMDBT) dissolved in octane, isooctane or toluene. The reactivity of different sulfur containing molecules in ODS was shown to increase in the sequence: thiophene<DBT<DMDBT. The main sulfur containing product of oxidation of these compounds was SO2. During the gas-phase ODS both processes of sulfur species oxidation and processes of their adsorption were observed and studied. Based on the conducted studies, different ODS process designs comprising its integration with adsorption and regeneration processes and with conventional hydrodesulfurization (HDS) process were proposed. One scheme is based on alternating regimes of ODS and catalyst regeneration in two reactors: sulfur is removed from organic feedstock by oxidation and adsorption in one reactor while simultaneous regeneration of the catalyst that has accumulated sulfur compounds takes place in another reactor. Two other schemes are based on joint use of ODS and HDS. The conventional HDS process is most effective for removal of low-boiling sulfur containing compounds reactive with respect to hydrogen, while removal of refractory sulfur compounds, such as DMDBT is more easily achieved by gas phase ODS. Thus the combination of these processes is expected to be most efficient for deep desulfurization of diesel fuel