A class-based approach to parallelization of legacy codes

Computation-intensive legacy codes for numerical models stand to benefit from application of parallel computing. However, parallelization of legacy codes poses special challenges. These codes are very large and complex. Manual parallelization has proven to be extremely time-consuming and error-prone. Furthermore, while a large number of parallelization tools exist, they cannot handle these complex legacy codes. Development of automatic parallelization tools for legacy codes remains a research area of considerable interest;This thesis describes a new approach to automatic parallelization of legacy codes. Our approach focuses on special classes of codes as opposed to parallelization of arbitrary codes. The advantage is that we are able to use high-level knowledge of the special class to manage the complexity of the parallelization problem. This approach provides a pragmatic solution for parallelization: it requires the user to specify the high-level knowledge, but automates tasks which are time-consuming, tedious, and error-prone for the user;Using this new approach, we have developed parAgent--a parallelizing tool which facilitates quick development of efficient parallel codes for legacy Fortran-77 codes based on the explicit time-marching finite difference model. parAgent has been used on several well-known and widely-used Mesoscale Meteorological codes. It took only a few weeks to parallelize each of these legacy codes. Qualitatively, the performance of parallelization have been found to be on par with manual parallelization;This new approach can be applied to a variety of problem domains. The key benefits are: substantial reuse of existing software and considerable saving of time and effort for developing efficient parallel code. Although the new approach and parAgent have been developed with parallelization as the main objective, the information provided by the tool can be used for various purposes. For example, the information about the underlying numerical method and the exchange of data is valuable to the application scientist

Bioluminescence emissions of firefly _Luciola praeusta_ Kiesenwetter 1874 (Coleoptera : Lampyridae : Luciolinae)

_In vivo_ emission and time-resolved spectra of firefly _Luciola praeusta_ Kiesenwetter 1874 (Coleoptera : Lampyridae : Luciolinae) have been recorded. The emission spectrum shows the FWHM value for this particular species to be 55 nm, which is significantly narrower than the _in vivo_ half widths reported till now. The time-resolved spectrum reveals that a flash, of duration about a hundred milliseconds, is in fact composed of a number of microsecond pulses. This result suggests that the speed of the enzyme-catalysed chemiluminescence reaction in the firefly for the emission of light is much faster than is believed to be

Bioluminescence emission of the firefly

We have recorded _in vivo_ emission and time-resolved spectra of the firefly species _Pyrophorus noctilucus_. The emission spectrum shows the FWHM value for this particular species to be 55 nm, which is significantly smaller than the half widths reported till now. The time-resolved spectrum reveals that a flash, of duration about a hundred milliseconds, is in fact composed of a number of microsecond pulses. This result suggests that the speed of the enzyme-catalyzed chemiluminescence reaction in the firefly for the emission of light is much greater than is believed to be

Competing mechanisms govern the thermal rectification behavior in semi-stochastic polycrystalline graphene with graded grain-density distribution

Thermal rectifiers are devices that have different thermal conductivities in opposing directions of heat flow. The realization of practical thermal rectifiers relies significantly on a sound understanding of the underlying mechanisms of asymmetric heat transport, and two-dimensional materials offer a promising opportunity in this regard owing to their simplistic structures together with a vast possibility of tunable imperfections. However, the in-plane thermal rectification mechanisms in 2D materials like graphene having directional gradients of grain sizes have remained elusive. In fact, understanding the heat transport mechanisms in polycrystalline graphene, which are more practical to synthesize than large-scale single-crystal graphene, could potentially allow a unique opportunity to combine with other defects and designs for effective optimization of the thermal rectification property. In this work, we investigated the thermal rectification behavior in periodic atomistic models of polycrystalline graphene whose grain arrangements were generated semi-stochastically in order to have different gradient grain-density distributions along the in-plane heat flow direction. We employed the centroid Voronoi tessellation technique to generate realistic grain boundary structures for graphene, and the non-equilibrium molecular dynamics simulations method was used to calculate the thermal conductivities and thermal rectification values. Additionally, detailed phonon characteristics and propagating phonon spatial energy densities were analyzed based on the fluctuation-dissipation theory to elucidate the competitive interplay between two underlying mechanisms that determine the degree of asymmetric heat flow in graded polycrystalline graphene.Comment: This is an early draft of our manuscript intended to be submitted to a peer-reviewed journal after some more updates by the authors, and the submission will be updated accordingly here as wel

Nanotech for clean water: an alternative approaches to control water pollution

Wastewater is any water that has been adversely contaminated by organic pollutants, bacteria and microorganisms, industrial effluent or any compound that deteriorated its initial quality.  The recent advances and application of nanotechnology for waste water treatment is dealt briefly in this review. During treatment of municipal waste water it has to consider all aspect related to contamination and has to ensure that water is free from all harmful substances. Nanotechnology has new procedures for the treatment of waste water. These techniques are fabrication of membrane from nanomaterials and use of catalyst for decomposition of noxious compound in water

Construction of an eco-friendly water treatments method by utilizing recycled materials- A review.

The most problematic issue of rural areas is the provision of clean water at a relatively low cost and energy rates. Industries discharge chemical effluents that contaminate existing water bodies. Chlorination may be one solution but are not employed in mass as they are less convenient to use. People die out of water borne diseases which in itself act as a source of motivation for resolving and analyzing the problem as soon as possible. In the present article, the demand of water treatment process that is chemical free, inexpensive, and simple to build has been increasing with the rise in population and pollution levels has been reviewed