Neizotropni kozmološki modeli s viskoznom tekućinom i tokom topline u Saez-Ballesterovoj teoriji gravitacije

We discuss the field equations in Saez-Ballester scalar-tensor theory of gravitation for a Bianchi type-V model filled with viscous fluid together with heat flow. We obtain two classes of cosmological solutions by applying a special law of variation of Hubble\u27s parameter which yields a constant value of deceleration parameter. One class of solutions corresponds to a model of universe which evolves from a big-bang type singularity at t=0 and expands with power-law expansion. The other class of solutions represents an universe expanding exponentially having singularity in the infinite past. The physical and kinematical features of the models are discussed. We observe that the models of the universe in two types of cosmologies are compatible with the results of recent observations.Razmatramo jednadžbe polja u Saez-Ballesterovoj skalarno-tenzorskoj teoriji gravitacije za Bianchijev model tipa V s viskoznom tekućinom i tokom topline. Postigli smo dvije vrste kozmoloških rješenja primjenom posebne relacije za promjene Hubbleovog parametra koje vode na stalnu vrijednost parametra usporavanja. Jedna vrsta rješenja odgovara modelu svemira koji se razvija iz singularnosti tipa velikog praska u t = 0 i širi se prema potencijalnom zakonu. Druga vrsta rješenja predstavlja svemir koji se širi eksponencijalno a singularnost mu je u beskonačnoj prošlosti. Raspravljaju se fizičke i kinematičke osebine oba modela. Nalazimo da su ova dva modela svemira u skladu s nedavnim opažanjima

Neizotropni kozmološki modeli s viskoznom tekućinom i tokom topline u Saez-Ballesterovoj teoriji gravitacije

We discuss the field equations in Saez-Ballester scalar-tensor theory of gravitation for a Bianchi type-V model filled with viscous fluid together with heat flow. We obtain two classes of cosmological solutions by applying a special law of variation of Hubble\u27s parameter which yields a constant value of deceleration parameter. One class of solutions corresponds to a model of universe which evolves from a big-bang type singularity at t=0 and expands with power-law expansion. The other class of solutions represents an universe expanding exponentially having singularity in the infinite past. The physical and kinematical features of the models are discussed. We observe that the models of the universe in two types of cosmologies are compatible with the results of recent observations.Razmatramo jednadžbe polja u Saez-Ballesterovoj skalarno-tenzorskoj teoriji gravitacije za Bianchijev model tipa V s viskoznom tekućinom i tokom topline. Postigli smo dvije vrste kozmoloških rješenja primjenom posebne relacije za promjene Hubbleovog parametra koje vode na stalnu vrijednost parametra usporavanja. Jedna vrsta rješenja odgovara modelu svemira koji se razvija iz singularnosti tipa velikog praska u t = 0 i širi se prema potencijalnom zakonu. Druga vrsta rješenja predstavlja svemir koji se širi eksponencijalno a singularnost mu je u beskonačnoj prošlosti. Raspravljaju se fizičke i kinematičke osebine oba modela. Nalazimo da su ova dva modela svemira u skladu s nedavnim opažanjima

A Review on Gamification in e-learning: Effects and Challenges

Information technology has brought us a great deal of technological advancement, opening up endless possibilities for distance education. E-Learning platforms make it possible to connect people around the globe. Using the various technologies that are available, Gamification enhances the performance of e-learning platforms. Gamification of e-learning platforms helps in providing an engaging learning experience for users of all ages. Applying gamification in a non-gaming environment motivates students and also keeps them engaged in learning. This paper summarizes various game elements such as points, leader boards, badges, provided to the users for better e-learning experience by gamifying the environment and discussing the impact of gamification

Narrow-Angle and Wide-Angle Astrometry via Long Baseline Optical/Infrared Interferometers

Long baseline optical/infrared interferometers, such as the Mark III Stellar Interferometer on Mt. Wilson and the ASEPS-0 Testbed Interferometer on Palomar Mountain, California, have good capabilities for narrow-angle and wide-angle astrometry with very high precision. Using the Mark III Interferometer many spectroscopic binaries became “visual” for the first time. The measurement accuracy of angular separation is 0.2 mas, the smallest separation measured between two components is 2 mas, the maximum magnitude difference is 4 mag, and the smallest semimajor axis is 4 mas. Such high angular resolution and dynamic range have been used to determine stellar masses with precision of 2% and differential stellar luminosities to better than 0.05 mag for separations of less than 0.″2. For some binary stars, not only have the systems been resolved, but also the diameter of the primary component has been determined, yielding direct measurements of stellar effective temperature with high accuracy. For parallax determination, the precision is 1 mas or better and is unaffected by interstellar extinction. For wide-angle astrometry with the Mark III interferometer, the observation results yielded average formal 1σ errors for FK5 stars of about 10 mas. Presently a new infrared interferometer, the ASEPS-0 Testbed Interferometer on Palomar Mountain is under construction, and is being optimized to perform high accuracy narrow-angle astrometry using long baseline observations at 2.2 μm, with phase referencing for increased sensitivity. The goal is to demonstrate differential astrometric accuracies of 0.06–0.1 mas in order to allow for detection of extra-solar planets in the near future

Multipoint boundary value problem for a coupled system of psi-Hilfer nonlinear implicit fractional differential equation

This study examines the existence and uniqueness of the solution to the coupled system of the ψ-Hilfer nonlinear implicit fractional multipoint boundary value problem. The uniqueness is shown by the Banach contraction principle, and the existence is shown by Krasnosel’skii’s fixed point theorem in a special working space. An example is presented to verify our results. The existence and uniqueness of the solution are analysed graphically

LEKSIKON ETNOBOTANI BAHASA JAWA

Language reflects human conceptualisation, human interpretation of the world. This paper describes lexicons ethnobothany in Javanese in terms of the Javanese speaker\u27s conceptualisation/interpretation of the plants world. In this paper the ethnobotanical lexicons in Javanese are also analyzed in terms of the general principles of ethnobotanical lexicons across languages. Keyword: ethnobotanical - category - lexicons.

DEVELOPMENT OF PNEUMATIC LAUNCHER

Compressed air is used to propel a grenade from a closed cavity. Pressure change in a closed environment will result in propelling of object from the closed chamber. The pneumatic source can be stored in a chamber for portability and even a live source can be directly connected to the gun. The grenade will accelerate with the compressed air, when the air is trying to escape in to the low-pressure atmosphere air. The acceleration of the grenade depends upon the pressure of the air and higher pressure will generate more acceleration. Inside the closed chamber if the air is supplied through a small opening and if the attachment is being attached to the opening then the pressure created will be less and the grenade will start rotating inside the chamber. To overcome this, that attachment should not be attached with the opening it should be placed over a very small distance from the gun, so that a vacuum will be produced from the atmosphere and the grenade could be launched at a high pressure