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We explore the dynamics of a time-variant prey–predator model of two species of fishes, namely Tenualosa ilisha(prey) and Macrognathus pancalus(predator). The prey exhibits anti-predatory behavior due to fear of predation. The prey equation is also equipped with age-based growth and harvestation terms to investigate the significance of maturity and harvest delay. The prey moves from saline water to freshwater for spawning, during which the predator feeds on an alternative food source. We explore the impact of this food source on the survival of prey. Starting with the sufficient conditions for positivity and boundedness of the solutions to the model, we find conditions for the existence of a stable global solution, periodic and almost periodic solutions. We find the range of existence for prey and predator populations and observe the interdependence between these values. According to our findings, just the fear of predation is enough to drive the prey population low. Even when the prey happens to be in an advantageous scenario, fear can still bring its population down, unless there are no or very few predators.

This paper considers a scenario-based approach, a stochastic ORPD formulation and solution that accommodates uncertain load demand, and solar power. The optimization tasks are based on the Modified Ant Line Optimizer (MALO) algorithm. PV system was used in place of the conventional thermal generator at bus 8, then the IEEE 30-bus system is modified. In addition, calculate the available solar power, and use the lognormal probability density function. In this paper, minimization of active power losses and voltage deviation are considered as objectives. This is delineated as an optimization problem by considering solar energy uncertainties and load uncertainties. Introducing solar energy sources to the power system along with the existing conventional sources to improve the performance of the system. An analysis was carried out using MALO to examine the proposed approach for IEEE 30-bus test system. The proposed method has been compared to other approaches and found to be effective.

We perform a detailed analysis of the behaviour of a non-autonomous prey–predator model where age-based growth with age discriminatory harvesting in prey and predator’s reliance upon alternative food in the absence of that particular prey are considered. We begin by deriving certain sufficient conditions for permanence and positive invariance and then proceed to construct a Lyapunov function to derive some constraints for global attractivity. With the help of continuation theorem, we arrive at the best fit criterion to prove the occurrence of a positive periodic solution. Moreover, using Arzela–Ascoli theorem, we formulate a proof for a unique positive solution to be almost periodic, and we carry out numerical simulation to verify the analytical findings. With the aid of graphs and tables, we show the nature of the prey–predator system in response to the alternative food and delays.

AbstractThe objective of this paper is to investigate the combined heat and mass transfer process near a vertical wavy semi-infinite surface embedded in a doubly stratified electrically conducting fluid-saturated Darcy porous medium under the influence of Soret and Dufour effects. The governing coupled non-dimensional partial differential equations are transformed to boundary layer equations using the two point local non-similarity transformation which is obtained by scale analysis. The resulting boundary layer equations are solved numerically by applying the Keller Box finite difference scheme. The heat and mass transfer has been analysed by plotting the Local, Average Nusselt and Sherwood numbers for various values of parameters influencing the model like: (Magnetic field effect), a(amplitude of wavy surface), and (Thermal and Mass Stratification), (Soret number), (Dufour number), Buoyancy ratio (B), Lewis number (Le).

A numerical study is carried out for the singularly perturbed generalized Hodgkin–Huxley equation. The equation is nonlinear which mimics the ionic processes at a real nerve membrane. A small parameter called singular perturbation parameter is introduced in the highest order derivative term. Keeping other parameters fixed, as this singular perturbation parameter approaches to zero, a boundary layer occurs in the solution. Three-step Taylor Galerkin finite element method is employed on a piecewise uniform Shishkin mesh to solve the equation. To procure more accurate temporal differencing, the method employs forward-time Taylor series expansion including time derivatives of third order which are evaluated from the governing singularly perturbed generalized Hodgkin–Huxley equation. This yields a generalized time-discretized equation which is successively discretized in space by means of the standard Bubnov–Galerkin finite element method. The method is third-order accurate in time. The code based on the purposed scheme has been validated against the cases for which the exact solution is available. It is also observed that for the Singularly Perturbed Generalized Hodgkin–Huxley equation, the boundary layer in the solution manifests not only by varying the singular perturbation parameter but also by varying the other parameters appearing in the model.

Ionic liquids (ILs) are salts that are liquid at low temperatures, usually including the region around room temperature. They are under intense investigation, especially as replacement solvents for reactions and separations, since they exhibit negligible vapor pressure and would not, therefore, contribute to air pollution. Clearly, basic thermophysical properties are vital for design and evaluation for these applications. We present density as a function of temperature, melting temperatures, glass-transition temperatures, decomposition temperatures, and heat capacities as a function of temperature for a series of 13 of the popular imidazolium-based ILs. The ionic liquids investigated here are 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium dicyanamide, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium tris(trifluoromethylsulfonyl)methide, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 2,3-dimethyl-1-ethylimidazolium bis(trifluoromethylsulfonyl)imide, 2,3-dimethyl-1-propylimidazolium bis(trifluoromethylsulfonyl)imide, 1-butyl-2,3-dimethylimidazolium tetrafluoroborate, and 1-butyl-2,3-dimethylimidazolium hexafluorophosphate. The properties follow quite reasonable trends. For instance, density decreases as the length of the alkyl chain on the cation increases. For a given cation, the density increases as the molecular weight of the anion increases for the anions studied here. Many of the ILs tend to subcool easily, forming glasses at very low temperatures rather than exhibiting crystallization or melting transitions. The thermal stability increases with increasing anion size, and heat capacities increase with temperature and increasing number of atoms in the IL.

The ability of subcritical water to support ionic chemistry is evident from the successful generation of 9-R-xanthenium (R = H and C6H5) carbocations at temperatures up to 330 °C from their respective alcohol precursors using laser flash photolysis. The intrinsic carbocation decay in the solvent was found to follow simple Arrhenius behavior at all temperatures, from ambient up to 330 °C. In addition, we determined the bimolecular rate constants for the reactions of xanthenium cation and 9-phenylxanthenium cations with amylamine, a neutral nucleophile. The activation energies of the two reactions were 21.6 ± 1.2 kJ mol^-1 and 18.2 ± 3.9 kJ mol^-1, respectively. More importantly, we found that the rate equations determined at high temperatures extrapolated extremely well to ambient conditions. Thus, we conclude that for ion/neutral isoCoulombic reactions, it would be reasonable to use low-temperature Arrhenius parameters to predict the rate constants in water at higher temperatures. Finally, we found that the effect of pressure on the bimolecular rate constants in the temperature range of 22−330 °C was negligible.

As there exist fuzzy matrices that do not have generalized inverses, it is useful to find those fuzzy matrices that admit generalized inverses. Some useful results on idempotent fuzzy matrices are established. Characterizations are obtained for fuzzy matrices having different types of generalized inverses. An algorithm for computing a generalized inverse of a given matrix (if it exits) is also provided and illustrated using numerical examples.

A reprocessing of 12 years of global data from the Advanced Very High Resolution Radiometers on board the afternoon-viewing NOAA series satellites (NOAA-7, 9, and 11) is taking place as part of the NASA/NOAA Pathfinder project. A Pathfinder AVHRR land data set is being produced which is composed of global, 8 km NDVI with associated reflectances, brightness temperatures, solar and scan geometry, and cloud estimation. This data set is being processed using the best available methods in order to produce a consistent time series of data of unprecedented quality. Methods used in processing include a cross-satellite calibration, navigation using an orbital model and updated ephemerides, and correction for Rayleigh scattering. The data will be available to the community as both daily and composite data, and analysis of this long time series is expected to provide insight into terrestrial processes, seasonal and annual variability, and methods for handling large volume data sets.

Prey population gathers together in a herd, thus possesses a social behavior. We consider the fact that the individuals of prey and predator interact mostly along the perimeter (boundary) of the pack (herd) formed in a 2D space or along the total surface area of the herd in a 3D space. Herding in prey implies the prey–predator interaction would be limited to the prey exposed on the outside of the herd. Thus prey on the inside of the herd has a diluted risk of predation. We model the three-dimensional shaped herds of hilsa (Tenualosa ilisha) fishes and their association with eel (Macrognathus pancalus) fishes (predator to hilsa) in a non-autonomous environment. Eel’s reliance on additional food sources during the absence of the hilsa has been modeled using Beddington DeAngelis functional response. We consider the delay in hilsa attaining sexual maturity and also the much-needed delay in collecting the harvest. We discuss various dynamical aspects such as persistence, the existence of a globally stable solution, and periodic solution. Through numerical simulation, we prove the significance of the presence of two-time delays for hilsa and the importance of the alternative food source for the predator. We do not see any difference in the dynamical aspects of time-variant hilsa–eel models with the cube and sphere-shaped herding in hilsa.

Under the Montreal protocol 1987 researchers worked on the possibility of alternative refrigerants like Hydroflourocarbon's [HFC's] and Hydrocarbon's[HC's] to replace refrigerants Chloroflourocarbon's [CFC's] and Hydrochlorofluorocarbons [HCFC's] in air-conditioning and cooling systems that are destroying the ozone layer. On October 15, 2016 one hundred and ninety plus countries including India came to an agreement called Kigali Amendment to phase out potent green house gases by 2045 there by preventing 0.5 C rise in global temperature by 2050. Under this agreement India agreed to a timeline to reduce the use of HFC's by 85% of their baseline by 2045. HFC's are a family of greenhouse gases that are largely used in refrigerators and air conditioners which have reduced the Ozone Depleting Potential [ODP] but increased the Global Warming Potential [GWP]. Refrigeration and its applications are important in almost all branches of industry, so engineers have to become aware of its principles, uses and limitations. Since the decade there are major changes in the choice of refrigerants due to environmental factors. This issue is on-going and new developments should be developed to decrease the environmental problems. So the aim of this paper is to present the experimental analysis of Coefficient of performance [COP] values using R134a [HFC] & R600a [HC] as Refrigerants in Domestic refrigerator using conventional and nonconventional energy sources. Based on the results, usage of R600a in domestic refrigerators will reduce the ODP and also GWP problems which fulfills the nominal requirements of human beings without any effects.