Power Line Communication Technologies: Modeling and Simulation of PRIME Physical Layer

Power Line Communications is a relatively new area of telecommunication. PLC employs full duplex methods for transmitting data over power lines as medium of transmission of electrical signals over a grid. PLC technologies are used in advanced meter reading, home automation and Public street lighting. Several PLC technologies classified based on the operational frequency range, are explored in this paper. PRIME is a new NBPLC system, which uses OFDM in its physical layer, for power line communication in the last mile. This work also focused on PRIME’s physical specifications, which was modeled in MATLAB/SIMULINK. In this paper, the performance of PRIME when its data is modulated using DQPSK and 4-QAM in four (4) channel models is shown.

Properties of the most metal-poor gas-rich LSB dwarf galaxies SDSS J0015+0104 and J2354-0005 residing in the Eridanus void

SDSS J0015+0104 is the lowest metallicity low surface brightness dwarf (LSBD) galaxy known. The oxygen abundance in its HII region SDSS J001520.70+010436.9 (at ~1.5 kpc from the galaxy centre) is 12+log(O/H)=7.07 (Guseva et al.). This galaxy, at the distance of 28.4 Mpc, appears to reside deeply in the volume devoid of luminous massive galaxies, known as the Eridanus void. SDSS J235437.29-000501.6 is another Eridanus void LSBD galaxy, with parameter 12+log(O/H)=7.36 (also Guseva et al.). We present the results of their HI observations with the Nancay Radio Telescope revealing their high ratios of M(HI)/L_B ~2.3. Based on the Sloan Digital Sky Survey images, we derived for both galaxies their radial surface brightness profiles and the main photometric parameters. Their colours and total magnitudes are used to estimate the galaxy stellar mass and ages. The related gas mass-fractions, f_g ~0.98 and ~0.97, and the extremely low metallicities (much lower than for their more typical counterparts with the same luminosity) indicate their unevolved status. We compare these Eridanus void LSBDs with several extreme LSBD galaxies residing in the nearby Lynx-Cancer void. Based on the combination of all their unusual properties, the two discussed LSBD galaxies are similar to the unusual LSBDs residing in the closer void. This finding presents additional evidence for the existence in voids of a4 figures, sizable fraction of low-mass unevolved galaxies. Their dedicated search might result in the substantial increase of the number of such objects in the local Universe and in the advancement of understanding their nature.Comment: 8 pages, 4 figures, 2 tables, accepted to MNRAS 02.04.2013. arXiv admin note: text overlap with arXiv:0909.134

Magnetic energy cascade in spherical geometry: I. The stellar convective dynamo case

We present a method to characterize the spectral transfers of magnetic energy between scales in simulations of stellar convective dynamos. The full triadic transfer functions are computed thanks to analytical coupling relations of spherical harmonics based on the Clebsch-Gordan coefficients. The method is applied to mean field $\alpha\Omega$ dynamo models as benchmark tests. From the physical standpoint, the decomposition of the dynamo field into primary and secondary dynamo families proves very instructive in the $\alpha\Omega$ case. The same method is then applied to a fully turbulent dynamo in a solar convection zone, modeled with the 3D MHD ASH code. The initial growth of the magnetic energy spectrum is shown to be non-local. It mainly reproduces the kinetic energy spectrum of convection at intermediate scales. During the saturation phase, two kinds of direct magnetic energy cascades are observed in regions encompassing the smallest scales involved in the simulation. The first cascade is obtained through the shearing of magnetic field by the large scale differential rotation that effectively cascades magnetic energy. The second is a generalized cascade that involves a range of local magnetic and velocity scales. Non-local transfers appear to be significant, such that the net transfers cannot be reduced to the dynamics of a small set of modes. The saturation of the large scale axisymmetric dipole and quadrupole are detailed. In particular, the dipole is saturated by a non-local interaction involving the most energetic scale of the magnetic energy spectrum, which points out the importance of the magnetic Prandtl number for large-scale dynamos.Comment: 21 pages, 14 figures, 1 table, accepted for publication in the Astrophysical Journa

Gelatin Properties of Goat Skin Produced by Calcium Hydroxide as Curing Material

Application of strong bases as curing materials has been widely applied in commercial gelatin industries, but the application of weak bases has not been much done. Application of strong bases as a treatment was not economical and assumed to affect human health. Studies were conducted on the properties of goat skin gelatin manufactured using weak base types of Ca(OH)2 and then compared with properties of commercial gelatin. Skins from Bligon goats of 1.5 to 2.5 years old was used as the raw materials and Ca(OH)2 100 g/l as curing materials. The 2x3 factorial completely randomized design (CRD) with three replications was used as a design study. Two curing times (2 and 4 days) and three concentrations (3, 6, 9% v/v) were used as treatments, and commercial gelatin (pure (P) by Merck, food grade (Fg) and pharmacy standards (Ps)) were used as control. Gelatin produced from goat skins using Ca(OH)2 had properties similar to that of commercial gelatin. The heavy metals (Pb, Cu and Zn) contained in goat skin gelatin still meet the INS standards. The optimum production of gelatin has been generated through the application of 4-day curing time at a concentration of 9% (v/v)

Extreme Mass Ratio Binary: Radiation reaction and gravitational waveform

For a successful detection of gravitational waves by LISA, it is essential to construct theoretical waveforms in a reliable manner. We discuss gravitational waves from an extreme mass ratio binary system which is expected to be a promising target of the LISA project. The extreme mass ratio binary is a binary system of a supermassive black hole and a stellar mass compact object. As the supermassive black hole dominates the gravitational field of the system, we suppose that the system might be well approximated by a metric perturbation of a Kerr black hole. We discuss a recent theoretical progress in calculating the waveforms from such a system.Comment: Classical and Quantum Gravity 22 (2005) S375-S379, Proceedings for 5th International LISA Symposiu