islam spread rapidly after its founding, encompassing much of north africa, the middle east, and southeast asia. the art of this vast region draws its distinctive character both from islam itself and from the diverse cultural traditions of the world’s muslims. because islam discouraged the use of figurative images, particularly in religious contexts- unlike christian art- islamic artists develo...

Several studies on photovoltaic systems focused on how it operates and energy required in operating it. Little attention is paid on its configurations, modeling of mean time to system failure, availability, cost benefit and comparisons of parallel and series–parallel designs. In this research work, four system configurations were studied. Configuration I consists of two sub-components arranged ...

We present evolutionary pathways for creating hot subdwarf OB (sdOB) stars from hierarchical triple configurations. use the population synthesis code Multiple Stellar Evolution (MSE) to follow stellar, binary, and gravitational dynamical evolution of triple-star systems. To ascertain effect outer tertiary, we also consider inner binary with tertiary component removed. find are able create sdOB ...

We explore the possibility that extrasolar planets might be found in the 1:1 mean-motion resonance, in which a pair of planets share a time-averaged orbital period. There are a variety of stable co-orbital configurations, and we specifically examine three different versions of the 1:1 resonance. In the first configuration, the two planets and the star participate in tadpole-type librations abou...

This exploratory paper considers the notion of a covering configuration and $G$-coverings which are coverings that quotients under semi-regular group action. We consider prime configurations, those cannot $G$-cover other before considering orbiconfigurations. These generalized in spirit an orbifold. derive some specific results as to when configurations well orbiconfiguration is bad - is, it be...

Virial theorem is important for understanding stellar structures. It produces an interesting connection between magnetic and gravitational energies. Using the general form of the virial theorem including the magnetic field (toroidal magnetic field), we may explain the solar dynamo model in relation to variations of the magnetic and gravitational energies. We emphasize the role of the gravitatio...

The potential-energy tensors for subsystems. IV. Homeoidally striated density profiles with a central cusp. Abstract. A general theory of homeoidally striated density profiles where no divergence occurs, is adapted to cuspy density profiles, with a suitable choice of the scaling density and the scaling radius. A general formulation of some physical parameters, such as angular-momentum vector, r...

Our ability to determine stellar ages from measurements of stellar rotation, hinges on how well we can measure the dependence of rotation on age for stars of different masses. Rotation periods for stars in open clusters are essential to determine the relations between stellar age, rotation, and mass (color). Until recently, ambiguities in v sin i data and lack of cluster membership information,...

We present a detailed discussion of our new 3D numerical models for the accretion of stellar winds on to Sgr A. In our most sophisticated models, we put stellar wind sources on realistic orbits around Sgr A, we include recently discovered ‘slow’ winds (vw ∼ 300 km s ), and we account for optically thin radiative cooling. We test our approach by first modelling only one phase ‘fast’ stellar wind...