Explicit,periodic and dispersive optical soliton solutions to the generalized nonlinear Schrödinger dynamical equation with higher order dispersion and cubic-quintic nonlinear terms

In this article, the nonlinear Schrödinger equation with higher order dispersion and nonlinear terms have been discussed analytically using extended Fan sub-equation method. The results hold numerous traveling wave solutions like optical, bright, dark, explicit, periodic and combined wave solutions with the aid of five parameters that are of key importance in elucidating some physical circumstance.     

A class of algebraically general solutions of the Einstein-Maxwell equations for non-null electromagnetic fields

The Einstein-Maxwell field equations for non-null electromagnetic fields are studied under the conditions that the null tetrad is parallelly propagated along both principal null congruences. It is shown that the resulting spacetime solutions are necessarily algebraically general. The twist-free solution found in a previous article is shown to be the most general twist-free solution. An expansionfree solution with twist and shear is also found.     

Molecular co-crystals of carboxylic acids, part 29. The effect of competitive interactions on adduct formation involving 2-aminopyrimidine: the crystal structure of the 1∶1 adduct of 2-aminopyrimidine with indole-2-carboxylic acid

The crystal structure of the 1∶1 adduct of 2-aminopyrimidine with indole-2-carboxylic acid has been determined by single crystal X-ray diffraction, revealing a novel interactive mode. The utility of 2-aminopyrimidine in formation of stable hydrogen-bonded networks with carboxylic acids is discussed and the modes of interaction are reviewed. Part 28.,Aust. J. Chem., 1997, (submitted).     

Sampling modulation technique in radio-frequency helium glow discharge emission source by use of pulsed laser ablation

An emission excitation source comprising a high-frequency diode-pumped Q-switched Nd:YAG laser and a radio-frequency powered glow discharge lamp is proposed. In this system sample atoms ablated by the laser irradiation are introduced into the lamp chamber and subsequently excited by the helium glow discharge plasma. The pulsed operation of the laser can produce a cyclic variation in the emission intensities of the sample atoms whereas the plasma gas species emit the radiation continuously. The salient feature of the proposed technique is the selective detection of the laser modulation signal from the rest of the continuous background emissions, which can be achieved with the phase sensitive detection of the lock-in amplifier. The arrangement may be used to estimate the emission intensity of the laser ablated atom, free from the interference of other species present in the plasma. The experiments were conducted with a 13.56 MHz radio-frequency (rf) generator operated at 80 W power to produce plasma and the laser at a wavelength of 1064 nm (pulse duration:34 ns, repetition rate:7 kHz and average pulse energy of about 0.36 mJ) was employed for sample ablation. The measurements resulted in almost complete removal of nitrogen molecular bands (N₂⁺ 391.44 nm). Considerable reduction (about 75%) in the emission intensity of a carbon atomic line (C I 193.03 nm) was also observed.     

Spectroscopic determination of sulphate in the presence of excess of nitrate and nitrite

The KBr pellet technique has been used for the determination of alkali metal sulphate in the presence of large excesses of nitrate and nitrite by measuring the absorption of the sulphate at 619 cm(-1). The sulphate can be determined in a 400-fold molar excess of nitrate and a 60-fold molar excess of nitrite with a relative standard deviation of about 5%.     

A novel method for designing nonlinear component for block cipher based on TD-ERCS chaotic sequence

A substitution box is used to induce nonlinearity in plaintext for encryption systems. Recently, the application of chaotic maps to encryption applications has resulted in some interesting nonlinear transformations. In this paper, we propose an efficient method to design nonlinear components for block ciphers that are based on TD-ERCS chaotic sequence. The new substitution box is analyzed for nonlinearity, bit independence, strict avalanche criterion, generalized majority logic criterion, and differential and linear approximation probabilities. The results show high resistance to differential and linear cryptanalysis in comparison to some recently proposed chaotic substitution boxes.     

A novel construction of substitution box using a combination of chaotic maps with improved chaotic range

The influential application of substitution boxes in secure communication and multimedia security attracted researchers to construct more robust substitution boxes. The advantage of using chaos in the secure communication is to get additional unpredictability and randomness in data. In this paper, substitution boxes are constructed with the help of chaotic system and linear fractional transformation. The 256 distinct values of each substitution box are then checked with the help of different available algebraic and statistical analyses. These tests evaluate the strength and application of substitution boxes in different encryption techniques. The results indicate the strength of anticipated technique.

     

Computational soliton solutions to $$$$-dimensional generalised Kadomtsev–Petviashvili and $$(2+1)$$(2+1)-dimensional Gardner–Kadomtsev–Petviashvili models and their applications

In this paper, we present a formalism to generate a family of interior solutions to the Einstein–Maxwell system of equations for a spherically symmetric relativistic charged fluid sphere matched to the exterior Reissner–Nordström space–time. By reducing the Einstein–Maxwell system to a recurrence relation with variable rational coefficients, we show that it is possible to obtain closed-form solutions for a specific range of model parameters. A large class of solutions obtained previously are shown to be contained in our general class of solutions. We also analyse the physical viability of our new class of solutions.