An automatic and efficient foreground object extraction scheme

This paper presents a method to differentiate the foreground objects from the background of a color image. Firstly a color image of any size is input for processing. The algorithm converts it to a grayscale image. Next we apply canny edge detector to find the boundary of the foreground object. We concentrate to find the maximum distance between each boundary pixel column wise and row wise and we fill the region that is bound by the edges. Thus we are able to extract the grayscale values of pixels that are in the bounded region and convert the grayscale image back to original color image containing only the foreground object

An inverse technique for reconstructing ocean’s density stratification from surface data

In this article, we propose an inverse technique that accurately reconstructs the ocean's density stratification profile simply from free surface elevation data. Satellite observations suggest that ocean surface contains the signature of internal tides, which are internal gravity waves generated by the barotropic tides. Since internal tides contain the information of ocean's density stratification, the latter can in principle be reconstructed from the free surface signature. We consider a simple theoretical model that approximates a continuously stratified ocean as discrete layers of constant buoyancy frequency; this facilitates the derivation of a closed-form dispersion relation. First, we numerically simulate internal tide generation for toy ocean scenarios and subsequently perform Space-Time Fourier Transform (STFT) of the free surface, which yields internal tide spectra with wavenumbers corresponding to the tidal frequency. The density profile is reconstructed by substituting these wavenumbers into the dispersion relation. Finally, we consider a more realistic situation with rotation, bottom topography, shear and density profiles representative of the Strait of Gibraltar. Density reconstruction in the presence and absence of shear are respectively found to be $90.2\%$ and $94.2\%$ accurate

Morpho-kinematic and photoionization models of the multipolar structures in planetary nebula NGC 6572

We have studied the planetary nebula (PN) NGC 6572 through 3D morpho-kinematic and photoionization modelling. The 3D morphology is reconstructed from the Hubble Space Telescope images in different narrow band filters and position-velocity spectra. The PN have a multipolar morphology consisting of highly collimated outflows. The nebular image show signatures of multiple lobes within a spiral-ring-like structure. The multipolar structure is modelled with two bipolar shells (axes ratios 5.5:1 and 3:1), having closed and opened lobes, respectively. A toroidal structure (radius:height = 1:3) surrounds the shells at the waist. The toroidal axis aligns with the major axes of the bipolar shells. Our study reveals the nebula to have a history of collimated polar outflow perpendicular to a higher density equatorial wind with the outflow seemingly have episodes of changing direction of ejection. We construct a photoionization model of NGC 6572 using the deep optical spectra obtained at the 2 m Himalayan Chandra Telescope. For the photoionization model, we configure the input shell geometry in form of a highly bipolar nebular shell with reference to the 3D morphology. Our photoionization model satisfactorily reproduces the observables. We estimate the nebular elemental abundances, and important characteristic parameters of the central star (e.g., effective temperature, luminosity, gravity, mass, etc.) and the nebula (e.g., hydrogen density profiles, radii, etc.). We compare the resolved H$\beta$, [O III], and [N II] profiles in the 4.2 m William Herschel Telescope with that from the photoionization model and find a good characteristic match.Comment: 14 pages, 10 figures, 6 table

CURATION AND MANAGEMENT OF CULTURAL HERITAGE THROUGH LIBRARIES

Libraries, museums and archives hold valuable collections in a variety of media, presenting a vast body of knowledge rooted in the history of human civilisation. These form the repository of the wisdom of great works by thinkers of past and the present. The holdings of these institutions are priceless heritage of the mankind as they preserve documents, ideas, and the oral and written records. To value the cultural heritage and to care for it as a treasure bequeathed to us by our ancestors is the major responsibility of libraries. The past records constitute a natural resource and are indispensable to the present generation as well as to the generations to come. Libraries preserve the documentary heritage resources for which they are primarily responsible. Any loss of such materials is simply irreplaceable. Therefore, preserving this intellectual, cultural heritage becomes not only the academic commitment but also the moral responsibility of the librarians/information scientists, who are in charge of these repositories. The high quality of the papers and the discussion represent the thinking and experience of experts in their particular fields. The contributed papers also relate to the methodology used in libraries in Asia to provide access to manuscripts and cultural heritage. The volume discusses best practices in Knowledge preservation and how to collaborate and preserve the culture. The book also deals with manuscript and archives issues in the digital era. The approach of this book is concise, comprehensively, covering all major aspects of preservation and conservation through libraries. The readership of the book is not just limited to library and information science professionals, but also for those involved in conservation, preservation, restoration or other related disciplines. The book will be useful for librarians, archivists and conservators. We thank the Sunan Kalijaga University, Special Libraries Association- Asian Chapter for their trust and their constant support, all the contributors for their submissions, the members of the Local and International Committee for their reviewing effort for making this publication possible

Radial magnetic field in a nonlinear dynamo model

Generation of magnetic field from seed magnetic field in a nonlinear rotating dynamo model. The initial magnetic field is axial-dipole. The important point is change of magnetic field structure as the field grows. The field go through a chaotic structure from initial axial-dipole structure and as soon as magnetic field starts effecting the flow, the field emerges as a large scale structure

Radial magnetic field in a kinematic dynamo model

Generation of magnetic field from seed magnetic field in a kinematic dynamo model, where Lorentz force has been dropped from momentum equation. The initial magnetic field is axial-dipole. After some time, the radial magnetic field loose the large-scale structure and dominated by small-components of the field

Energy exchanges between a two-dimensional front and internal wave modes

Fronts and near-inertial waves are energetic motions in the upper ocean that can interact and provide a route for kinetic energy (KE) dissipation of balanced oceanic flows. A quasilinear model is developed to study the KE exchanges between a two-dimensional geostrophically-balanced front undergoing strain-induced semigeostrophic frontogenesis and internal wave (IW) vertical modes. The quasilinear model is solved numerically for variable imposed strain magnitudes, initial IW vertical modes, and for both minimum frequency (near-inertial, NI) and high-frequency IWs. The front-IW KE exchanges are quantified separately during two frontogenetic stages -- an exponential sharpening stage that is characterized by a low Rossby number and is driven by the imposed geostrophic strain, followed by a superexponential sharpening stage that is characterized by an order-one Rossby number and is driven by the convergence of the ageostrophic secondary circulation. It is demonstrated that high-frequency IWs quickly escape the frontal zone and are very efficient at extracting KE from the imposed geostrophic strain field through the deformation shear production (DSP) mechanism. Part of the extracted KE is then converted to wave potential energy. Minimum frequency IWs remain locked to the frontal zone and therefore exchange energy with the ageostrophic frontal circulation. During the exponential stage, IWs extract KE from the geostrophic strain through DSP and transfer it to the frontal secondary circulation via the ageostrophic shear production (AGSP) mechanism. During the superexponential stage a newly identified mechanism, convergence production (CP), which is directly linked to the convergent secondary circulation, plays an important role in the NIW KE budget

Letter:Ocean bathymetry reconstruction from surface data using hydraulics theory

Here we propose a technique that successfully reconstructs ocean bathymetry from the free surface velocity and elevation data. This technique is based on the principles of open-channel hydraulics, according to which a sub-critical flow over a seamount creates a free surface dip. The proposed method recognizes that such free surface dip contains the signature of the bottom topography, hence inverts the free surface to reconstruct the topography accurately. We applied our inversion technique on re-analysis data, and reconstructed the Mediterranean and the Red sea bathymetries of $1/12\degree$ resolution with approximately $90$\% accuracy.Comment: Accepted for publication in Physics of Fluids (Letters

White Light Emission From Surface-Oxidized Manganese-Doped Zns Nanorods

Mn-doped ZnS nanorods synthesized on zinc foils by a solvothermal approach exhibited white light emission upon excitation in the UV range (300-330 nm). X-ray diffraction studies coupled with energy-dispersive X-ray analysis and X-ray photoelectron spectroscopy indicated the presence of a thin oxide layer on the Mn-doped ZnS nanorods. The diameters and lengths of the nanorods varied within the ranges 5-12 and 50-100 nm, respectively. The emitted white light was found to be the result of blue, green, and orange emission bands. The blue bands at ∼400 and 459 nm were attributed to sulfur vacancies and surface states, respectively. The green band at ∼511 nm was associated with the singly ionized oxygen vacancy of the ZnO shell layer. The orange emission originated from the 4T1-6A1 transition of the Mn2+ ions. Thus, the emissions from the Mn-doped ZnS core and the outer ZnO shell combine together to produce the white light. © 2008 American Chemical Society